Group Item; add ability to poulated domain_name

[graham-marcus]

In order to create active directory group the domain_name is not an input field available when creating the group item to add.
In group_item.py the option is not available can this be added as optional
def init(self, name=None):
self._domain_name = None

[graham-marcus]

Take this through to use
newgroupitem = server.groups.create_AD_group(newgroupitem)
where the newgroupitem object has the group name, import, domain, minimum site role options available to populate

[bcantoni]

Thanks for reporting/suggesting this -- I'll tag as a feature enhancement.

[shinchris]

Fix (#770) released with v0.15.0.