Fix only first group is processed in include list (Bug 1278013)

The change from Patric
(https://github.com/patrickpollet/mahara_ldap_sync/commit/13c3d419f2e9b9336297ae9a69d9e414af542a48)
has been ported

Allow spaces in the list of group names, e.g "users, teachers ,  tutors"

Change-Id: I31b13a44679442d58c2be80dffd828d90c60227f
Signed-off-by: Son Nguyen <son.nguyen@catalyst.net.nz>
Merge "Fix only first group is processed in include list (Bug 1278013)" into 1.8_STABLE