Merge branch 'hotfix/0.18.7'

* hotfix/0.18.7:
  * Updated gems
Converting templates to slim
added back html extension to slim templates
fixed templates
fixed all specs
Fixed itinerary thumbnail
Indent html for pretty debugging and do not sort attributes
Updated gems
Removed the slim prettifier because of uniformity between development and production layout (whitespaces)
More fixes to slim templates
fixed merge conflicts
Improved slim templates
Merge branch 'feature/slim' into develop

* feature/slim:
  Improved slim templates
  More fixes to slim templates
  Removed the slim prettifier because of uniformity between development and production layout (whitespaces)
  Updated gems
  Indent html for pretty debugging and do not sort attributes
  Fixed itinerary thumbnail
  added back html extension to slim templates fixed templates fixed all specs
  Converting templates to slim
Bumped up version number
updated changeling
updated gems
fixed turbolinks progress bar
fixed changelog
[ci skip]
* Updated gems
fixed merge conflicts
Ruby 2.1.5
Rails 4.2.0.rc3
Updated gems
fixed merge conflicts