Added country_supplies join table and associates

A link was created between countries and supplies via country_supplies.
Added migration to populate country_supplies for all items/countries
Added self.choices_for to Supply
Updated view to use Supply.choices_for
Updated choices_for to return all if arg is nil
fixed failed specs due to lack of country/supply relationship
Incoming shortcodes now must be country specific.

Incoming shortcodes must now be valid for the specific country
of the requester, else they are invalid and raise an exception.
Basic CRUD Interface
Updated button styling on view
removed debugging line
Updated tests/views/security for CountrySupply
Removed unneeded comments
improved code coverage via controller update
Merge pull request #364 from dhaskew/master

Added basic link between Supply / Country