Clean up elkstack's workarounds, java, deps

[martinb3]

• Remove the kibana.yml Kibana 4 workaround, now that kibana works again out of the box.
• Fixes #138, stop shipping Java wrappers. You must include java::default or get Java some other way.
• Clean up Berksfile. Many dependencies have since been fixed and/or released to Supermarket.
• Move back to logstash-forwarder pkg repos. Fixes #139, reverts https://github.com/rackspace-cookbooks/elkstack/commit/1fe2ff6de5a16715a2f54f569a4d5a5582bcb367 and https://github.com/rackspace-cookbooks/elkstack/commit/4106b75f727900a8b60ab7486b936af5e0d98449. Also remove golang deps.
• Fixes #135, stop making a distinction between a cluster install vs. a single all-in-one install without any agent.
• Merge default and cluster and single recipes. Default is now a clustered elkstack.
• Tags and search/discovery all operate off 'elkstack' tag. There is no more 'elkstack_cluster' tag.
• Fixed some of the rspec/chefspec unit tests as well.
• The lumberjack protocol will no longer be the default for Logstash to communicate, due to hosted chef changes and golang runtime SSL changes (fixes #56, #14).
• Don't test the lumberjack protocol with the server install by default, removes lumberjack test suite in .kitchen.yml
• Default to tcp/udp for communication between logstash instances, add flag: node['elkstack']['config']['agent_protocol'] = 'tcp_udp' # could also be lumberjack
• Don't try to load lumberjack secrets by default for agent, don't fail if they aren't present (rename recipes/_secrets.rb -> recipes/_lumberjack_secrets.rb)
• elkstack::acl recipe changes to support tcp/udp communication
• add logstash configs for tcp/udp communication
• remove tests for lumberjack.key/crt now from default test suites, remove extra data bags with lumberjack keypairs