#20 Fix superadmin layout to include correct js and css files

- We moved from application to application_desktop and application_phone
  for CSS and JS files.
- Updated superadmin layout with these changes.
Merge pull request #21 from bigbinary/fix-superadmin-layout

 #20 Fix superadmin layout to include correct js and css files
 Updated Rails to 4.1.6
Update Rails to 4.1.7

- sprockets-rails master is master is 3.0.0beta but Rails 4.1.x requires
  2.0.x.
- So fixed version of sprockets-rails.
Updated configuration files