0.5.0 release

[mattray]

• moved back to https://github.com/mattray/inspec-iggy as a community plugin
• provide DESIGN.md explaining the organization of the code
• disabled the inspec terraform extract subcommand until a more sustainable solution is determined
• rename lib/inspec-iggy/profile.rb to profile_helper.rb
• switch from 'eq' to 'cmp' comparators https://github.com/mattray/inspec-iggy/issues/23
• enable minimal Azure support. This needs to be refactored with support for Resource Packs.
• refactor out JSON parsing into file_helper.rb
• add support for remote .tfstate and .cfn files via Iggy::FileHelper.fetch https://github.com/mattray/inspec-iggy/issues/3
• Sync and upgrade InSpec's .rubocop.yml and associated code cleanups