Refs #351: Adds ability to sync course group members via ldap, and fixes ldap sync to work with overlapping enrolment periods.
Refs #351: This has evolved into a rewrite of how the LDAP sync works
Refs #351: Adds course group synchronization to LDAP course sync. Updates course audience ldap sync cronjob to work with new sync class.
Refs #351: Adds required constants to settings file
Removes instantiation of class in the header. Fixes the uninitialized SUFFIX variable to use the private property.
Merge pull request #427 from EntradaProject/feature-ldap-sync-updates

Refs #351: Adds ability to sync course group members via ldap, and fixes...