Fixed User.groups method from calling an attribute getter that sometimes does not exist (when the user belongs to no groups).
Small bugfix to allow setting of attributes for persistance

Bug fix to allow for setting of object attributes to allow for
persistance back to ActiveDirectory
Merge remote-tracking branch 'nicjp/master'; commit 'd964e9f8aa55d91192ffd00961f0ab192381b87d' into HEAD