Move current user's profile data from $rootScope to UserService

We basically moved all the user data (such as profile info, auth info,\
logging in/out functions) to an external UserService that we can inject into
any controller. This keeps the data perfectly synchonized, and clears up our
root and child scopes.

All of the unused $rootScope injections were removed as a result.

Each child scope can now access user data via $scope.user.profile and
$scope.user.auth