Changes

1. Update json_api_client to be compatible with Ruby 2.7
2. Remove unused or unneeded monkey-patching

Updates json_api_client run time dependency to match flex-ruby-gem version v0.9.0

Allow bundler to resolve to any mime-types version

Updates json_api_client run time dependency to match flex-ruby-gem version v0.6.55

Release includes updates from the following PRs:

• Update json_api_client gem to match the flex-ruby - #5
• Issue: Updates inline with Deployment Engine rails 5 upgrade - #7
• Issue: Pipeline Integration - #3

• Adds Pipeline model