Fixes #170 - implement usergroups
Added migrationAdded testsAdded MVC filesAdded the routes as wellAdded the program logic and additional viewsAdded RESTful actions for update and createAdded validations to ensure that usergroup.name and user.login do not collide...
renamed some variables
corrected typo
environments_controller_test on green
realigned models to use :though and habtm when it made sense, setup basic AS controllers to support that