Updates in api for roles and permissions

 - usergroups#show lists associated roles
 - listing available resource types
 - filters#show lists associated roles
 - filters#index lists associated roles and permissions and orders the results
 - pagination in permissions#index
 - missing parameters in apidocs for usergroups and roles
 - required name for usergroups
@tstrachota, I agree with @eLobato's commits to use `refute` rather than `assert !`