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...

updated incorrect url path, refs #179

fixes #257 - When creating a new hostgroup, it fails if I add a parameter when creating

yet another fix for #216

fixes #216 - Validate uniqueness of a parameter name for Individual hosts

Fixes #240 - Clone operation highlights changes correctly

The clone operation no longer flags edits as errors. This looks better.

fixes #233 - In the "Show" page for a Host, Build link should not be visible when Unattended is false.

Fixes #179 - allow mass assignment of parameters and host groups.
Greatly inspired by Ashay Humane <ashay.humane@gmail.com> at 5c2e395c

fixes #180 - Query to return more information

fixes #223 - When a host update has errors then the render :edit loses required variables