Revert "Merge branch 'feature/use-rails-assets-gem-source'"

This reverts commit e52661ea099c129942b73be79adfb019910dbeca, reversing
changes made to 70c7a5576c30d16b349739f7fb904baa02b8d609.
Upgrade to Rails 4.1.5
Scope position to collection
Add index to position of collections and collection wallpapers
Merge branch 'bug/fix-position-db-index'
Install vue and superagent

Reorganize file structure

Refactor wallpaper list

Revert bourbon and bootstrap scss

Refactor css

Refactor favourite button

Add element cloaking

Debug in development, show loading indicator

Implement toggle favourite api and frontend toggling

Disable toggle button during active request