add feature test: user may logout when logged in
add feature test: user cannot register with invalid arguments
add feature test: user cannot create fridge with invalid fridge name
edit feature test scenario: user can create fridge item when they are not the original fridge creator
add feature tests: fridge creator cannot add user to fridge when already a friend of friend, fridge creator cannot add non-existant user to fridge
add feature tests: user can add item to fridge with valid item name and category; user cannot add item to fridge with invalid fridge item
add feature test: friend of fridge can add other users to friended fridge
Merge pull request #17 from gopher-snakes-2013/add-feature-tests

Add feature tests