Added has_many relationships for {:blocked,:accepted}_user_friendships and corrected the :requested_user_friendships through parameter
Added tests for the new relationships
Added a new user fixture
Added new user friendship fixture for blocked state
Added tests for the parameter list of the #index method (case for blocked, pending, requested and accepted states)
Added some links to use the new parameter list
 Defined a private method friendship_association to handle the different friendship states for the list parameter of the #index method