Fixes #170 - implement usergroups

Added migration
Added tests
Added MVC files
Added the routes as well
Added the program logic and additional views
Added RESTful actions for update and create
Added validations to ensure that usergroup.name and user.login do not collide...

removing show action in places it doesn't make sense, and minor visual changes

fixes #207 - remove activescaffold from Parameters settings

added the common parameter tests