Merge branch 'release/2.7.0' into develop

* release/2.7.0:
  I mean... remove Gemfile.lock! [ci skip]
  Do not check Gemfile.lock [ci skip]
  * Updated README * Updated CONTRIBUTING guidelines * Added .editorconfig [ci skip]
  * [dev] Removed active_record from dummy test application * [dev] Removed debugger and sqlite dependency
  Respond.js 1.4.2
  Support for ruby 2.1
Merge branch 'hotfix/2.7.1' into develop

* hotfix/2.7.1:
  * Fixed license SPDX ID in gemspec
Merge branch 'hotfix/2.7.2' into develop

* hotfix/2.7.2:
  * Reformatted changelog
* Bootstrap v3.1.0
* Updated Bootstrap license to MIT
Merge branch 'release/2.8.0'

* release/2.8.0:
  * Bootstrap v3.1.0 * Updated Bootstrap license to MIT