Add Delete buttons and delete routes to all database models

[postmodern]

There should be delete routes for all /db/.../:id routes. Also add Delete buttons to all show.erb views.

• [x] views/db/advisories/index.erb
• [x] views/db/advisories/show.erb
• [x] views/db/asns/index.erb
• [x] views/db/asns/show.erb
• [x] views/db/credentials/index.erb
• [x] views/db/credentials/show.erb
• [x] views/db/email_addresses/index.erb
• [x] views/db/email_addresses/show.erb
• [x] views/db/host_names/index.erb
• [x] views/db/host_names/show.erb
• [x] views/db/ip_addresses/index.erb
• [x] views/db/ip_addresses/show.erb
• [x] views/db/mac_addresses/index.erb
• [x] views/db/mac_addresses/show.erb
• [x] views/db/open_ports/index.erb
• [x] views/db/open_ports/show.erb
• [x] views/db/organizations/index.erb
• [x] views/db/organizations/show.erb
• [x] views/db/oses/index.erb
• [x] views/db/oses/show.erb
• [x] views/db/passwords/index.erb
• [x] views/db/passwords/show.erb
• [x] views/db/people/index.erb
• [x] views/db/people/show.erb
• [x] views/db/phone_numbers/index.erb
• [x] views/db/phone_numbers/show.erb
• [x] views/db/ports/index.erb
• [x] views/db/ports/show.erb
• [x] views/db/services/index.erb
• [x] views/db/services/show.erb
• [x] views/db/software/index.erb
• [x] views/db/software/show.erb
• [x] views/db/software_vendors/index.erb
• [x] views/db/software_vendors/show.erb
• [x] views/db/street_addresses/index.erb
• [x] views/db/street_addresses/show.erb
• [x] views/db/url_query_param_names/index.erb
• [x] views/db/url_query_param_names/show.erb
• [x] views/db/url_schemes/index.erb
• [x] views/db/url_schemes/show.erb
• [x] views/db/urls/index.erb
• [x] views/db/urls/show.erb
• [x] views/db/user_names/index.erb
• [x] views/db/user_names/show.erb
• [x] views/db/vulns/index.erb
• [x] views/db/vulns/show.erb

[postmodern]

Implemented by PR #95 and #96.