Fixed variable scope bug in optionable concern

- With tidying up of the optionable concern
- CSS manifest set to ignore subdirectories
- Added therubyracer
- Updated to Ruby 2.1 after testing, and after moving to a Linux
development machine from Windows.
Disabled turbolinks

- Although these did speed up page loading, the overall user experience
is deteriorated in production because of lack of feedback on link click.