add route for custom layouts (LP India, etc)
changed variable names, cleaned up to pass tests
added 'defaults' to layout support hashes
 formatted routes file. added config hash for old routes
moved js-nav--primary outside of if statement for injecting custom menus
Add helper function and tests to clean up layout_support
Send all preview routes through /layouts/
Refactor routes/partials

Includes:
  - Making app_core configurable
  - Normalise head routes/partials
  - Normalise header routes/partials
  - Normalise footer routes/partials
Merge pull request #793 from lonelyplanet/bt-india

Bt india