Added to_param to the user model
Added a test for to_param
Modified the test to use to_param
Added a link to the friendship creation page
Added link_to also to the image, modified the link_to param to use to_param
Created a minimal form for the new user friendship page
Added case for :error
Modified the devise routes and deleted some comments
Created the create method and added a check for an invalid friend_id
Created tests for the create method and modified the tests for the new method