Replaces the $http service calls with promise based methods
of the client-side UsersService for the following:
Users Change Password
Users Manage Social Accounts
Users Password Forgot
Users Password Reset
Users Signup
Users Signin
Modifies tests to reflect changes.
Closes#1479
Fixes the issue with the previous state not being recorded, when the
unauthenticated user is redirected to the signin state, when trying to
access a restricted route.
Added a function that stores the provided state & state params, in the
$state.previous object. This has been implemented in the
$stateChangeSuccess event, and the callback of the $state.go transition
when the user is not allowed to access the requested route.
