fixes #4290 add validation for user group max name length of 255
fixes #3996 Support to assign both cores and CPUs to VMWare guests
fixes #4442 - returning nil plays nice with try_to_login.
fixes #4194, #4459 - add main_app to root_path references for isolated engines
fixes #4583 - Added Environment name to rundeck output
fixes #3221 - add missing attributes to hostgroup show response
fixes #4485 prevents undefined method when cloning a host
fixes #4581 Implement available_networks API for VMware
Usergroups can be linked to an LDAP auth_source. This allows usergroups
to be on sync with its equivalent LDAP usergroup.

Relation between auth_sources and usergroups

Tests, validations, and actual LDAP queries

Rake task to periodically refresh LDAP user groups

Adding LDAP users is done through User.where, not iterating through all possible users

Migration for groups/user OU, recursive usergroup search

Non recursive LDAP rake task

Check against LDAP aliases, or other empty results

Remove code from other branch