Merge pull request #316 from Skud/crop-hierarchy-caching

Added caching of full crop hierarchy
Added referral_code to Order

Also added validation (alphanumeric), but we're fairly lax about
whitespace and case, and clean up for them if they make minor errors.
added referral_code to order form/checkout code
moved admin order search into a model method
Added referral code search to admin forms
Added tests for admin order controller
Fixed up db/schema to remove spurious payments table
add referral code to order admin table
Made li list style dots more specific

We set all li elements to use list-style disc, but it was affecting our
navbar.  Changed it to use a specific class in the crop hierarchy (where
we actually cared about it).
Fixed navbar display CSS

1) Made sure padding is applied to the body *only* for the larger screen
sizes (by doing so before the responsive CSS is loaded)

2) Fixed indentation on the footer, which was incorrectly putting it
inside the main body container, and thus making it do this weird
narrowing thing at smaller screen sizes.
Merge pull request #318 from Skud/order_referral_code

Order referral code
Merge pull request #319 from Skud/css-fixes

Css fixes
added error message if your referral code has invalid chars
removed spurious puts
Merge pull request #320 from Skud/order_referral_code

Order referral code
Merge pull request #321 from Growstuff/dev

Production push: order referral codes and some CSS fixes