Bump all plugins dependency on `sensu-plugin` to 2.0

[majormoses]

Bump all plugins dependency on sensu-plugin to 2.0

This is a breaking change and would be across all plugins and needs to be done with care, I see the following as a set of prerequisite before doing this:

• [ ] ensure that all plugins can successfully build against ruby 2.4 (add testing of 2.4.1 to travis has been started)
• [ ] ensure that all plugins can execute successfully against ruby 2.4

When we do this we leave behind all sensu installs of < 0.29 which while I don't have numbers to back me on are probably a majority of sensu installs so this should not be done lightly and will require at least 1 and in fair number of cases 2 breaking changes to every single plugin.

What this means for Sensu admins

• Remember to always pin your Sensu system and your gems with specific versions
• Be aware that 0.29 and above use Ruby 2.4 and plugins need to be compatible with this version
• If you want to contribute please checkout #27, #29 and reach out to a maintainer if you have questions (@majormoses @eheydrick @mbbroberg)

EDIT: we should pin sensu-plugin to ~> 2.5 to pull in the latest and greatest.

[majormoses]

• [x] sensu-plugins-ansible
• [x] sensu-plugins-apache
• [x] sensu-plugins-aws
• [x] sensu-plugins-beanstalk
• [x] sensu-plugins-bigpanda
• [x] sensu-plugins-bluepill
• [x] sensu-plugins-campfire
• [ ] sensu-plugins-cassandra
• [ ] sensu-plugins-ceph
• [ ] sensu-plugins-cgroups
• [ ] sensu-plugins-chatwork
• [ ] sensu-plugins-chef
• [ ] sensu-plugins-clockworksms
• [ ] sensu-plugins-conntrack
• [x] sensu-plugins-consul
• [ ] sensu-plugins-couchbase
• [ ] sensu-plugins-couchdb
• [ ] sensu-plugins-cpu-checks
• [ ] sensu-plugins-cucumber
• [ ] sensu-plugins-dashing
• [ ] sensu-plugins-datadog
• [ ] sensu-plugins-dcos
• [ ] sensu-plugins-dhcp
• [ ] sensu-plugins-disk-checks
• [ ] sensu-plugins-dns
• [ ] sensu-plugins-docker
• [ ] sensu-plugins-dovecot
• [ ] sensu-plugins-eep
• [ ] sensu-plugins-elasticsearch
• [ ] sensu-plugins-entropy-checks
• [ ] sensu-plugins-environmental-checks
• [ ] sensu-plugins-erlang
• [ ] sensu-plugins-etcd
• [ ] sensu-plugins-execute
• [ ] sensu-plugins-eye
• [ ] sensu-plugins-feature-requests
• [ ] sensu-plugins-filesystem-checks
• [ ] sensu-plugins-flowdock
• [ ] sensu-plugins-fluentd
• [ ] sensu-plugins-freeradius
• [ ] sensu-plugins-ftp
• [ ] sensu-plugins-gearman
• [ ] sensu-plugins-geckoboard
• [ ] sensu-plugins-gelf
• [ ] sensu-plugins-github
• [ ] sensu-plugins-gluster
• [ ] sensu-plugins-golang
• [ ] sensu-plugins-google-spreadsheet
• [ ] sensu-plugins-gpg
• [ ] sensu-plugins-graphite
• [ ] sensu-plugins-graylog
• [ ] sensu-plugins-growthforecast
• [ ] sensu-plugins-haproxy
• [ ] sensu-plugins-hardware
• [ ] sensu-plugins-hbase
• [x] sensu-plugins-hipchat
• [x] sensu-plugins-http
• [ ] sensu-plugins-hubot
• [ ] sensu-plugins-icecast
• [ ] sensu-plugins-iis
• [ ] sensu-plugins-imap
• [ ] sensu-plugins-imkayac
• [ ] sensu-plugins-influxdb
• [ ] sensu-plugins-io-checks
• [ ] sensu-plugins-ipmi
• [ ] sensu-plugins-ipvs
• [ ] sensu-plugins-irc
• [ ] sensu-plugins-java
• [ ] sensu-plugins-jenkins
• [ ] sensu-plugins-jolokia
• [ ] sensu-plugins-kannel
• [ ] sensu-plugins-kegbot
• [ ] sensu-plugins-kubernetes
• [ ] sensu-plugins-ldap
• [ ] sensu-plugins-librato
• [ ] sensu-plugins-load-checks
• [ ] sensu-plugins-logs
• [ ] sensu-plugins-logstash
• [ ] sensu-plugins-lvm
• [ ] sensu-plugins-lxc
• [ ] sensu-plugins-mackerel
• [ ] sensu-plugins-mailer
• [ ] sensu-plugins-mailgun
• [ ] sensu-plugins-memcached
• [ ] sensu-plugins-memory-checks
• [ ] sensu-plugins-mesos
• [ ] sensu-plugins-messagemedia
• [x] sensu-plugins-mongodb
• [ ] sensu-plugins-monit
• [ ] sensu-plugins-mysql
• [ ] sensu-plugins-nbzget
• [ ] sensu-plugins-netscaler
• [ ] sensu-plugins-network-checks
• [ ] sensu-plugins-newrelic
• [ ] sensu-plugins-nginx
• [ ] sensu-plugins-nrpe
• [ ] sensu-plugins-ntp
• [ ] sensu-plugins-nvidia
• [ ] sensu-plugins-officehours
• [ ] sensu-plugins-openldap
• [ ] sensu-plugins-openstack
• [ ] sensu-plugins-opentsdb
• [ ] sensu-plugins-openvpn
• [ ] sensu-plugins-opsgenie
• [ ] sensu-plugins-pacemaker
• [x] sensu-plugins-pagerduty
• [ ] sensu-plugins-percona
• [ ] sensu-plugins-php-fpm
• [ ] sensu-plugins-pingdom
• [ ] sensu-plugins-ponymailer
• [ ] sensu-plugins-postfix
• [ ] sensu-plugins-postgres
• [ ] sensu-plugins-process-checks
• [ ] sensu-plugins-puma
• [ ] sensu-plugins-puppet
• [ ] sensu-plugins-pushover
• [ ] sensu-plugins-qmail
• [x] sensu-plugins-rabbitmq
• [ ] sensu-plugins-raid-checks
• [ ] sensu-plugins-redis
• [ ] sensu-plugins-request-tracker
• [ ] sensu-plugins-resque
• [ ] sensu-plugins-rethinkdb
• [ ] sensu-plugins-riak
• [ ] sensu-plugins-riemann
• [ ] sensu-plugins-rspec
• [ ] sensu-plugins-selinux
• [x] sensu-plugins-sensu
• [ ] sensu-plugins-sentry
• [ ] sensu-plugins-serverspec
• [ ] sensu-plugins-sftp
• [ ] sensu-plugins-sidekiq
• [ ] sensu-plugins-signifai
• [ ] sensu-plugins-sip
• [ ] sensu-plugins-skel
• [ ] sensu-plugins-skyline
• [ ] sensu-plugins-slack
• [ ] sensu-plugins-sms
• [ ] sensu-plugins-snmp
• [ ] sensu-plugins-solr
• [ ] sensu-plugins-splunk
• [ ] sensu-plugins-springboot
• [ ] sensu-plugins-ssl
• [ ] sensu-plugins-statuspage
• [ ] sensu-plugins-strongswan
• [ ] sensu-plugins-supervisor
• [ ] sensu-plugins-switchvox
• [ ] sensu-plugins-syslog-ng
• [ ] sensu-plugins-telapi
• [ ] sensu-plugins-telegram
• [ ] sensu-plugins-tempodb
• [ ] sensu-plugins-tomcat
• [ ] sensu-plugins-trafficserver
• [ ] sensu-plugins-tripwire
• [ ] sensu-plugins-twemproxy
• [ ] sensu-plugins-twilio
• [ ] sensu-plugins-twitter
• [ ] sensu-plugins-ubiquiti
• [ ] sensu-plugins-uchiwa
• [ ] sensu-plugins-unicorn
• [ ] sensu-plugins-ups
• [ ] sensu-plugins-uptime-checks
• [ ] sensu-plugins-varnish
• [ ] sensu-plugins-victorops
• [ ] sensu-plugins-vmstats
• [ ] sensu-plugins-vsphere
• [ ] sensu-plugins-windows
• [ ] sensu-plugins-wordpress
• [ ] sensu-plugins-xen
• [ ] sensu-plugins-xmpp
• [ ] sensu-plugins-zendesk
• [ ] sensu-plugins-zookeeper