Remove Qgroup model and make the qgroup as a charfield of share model. Create a
new datastore.in and initial south migration file.
Fixes #36

Update the API view code to not use the deleted Qgroup model.
Merge branch 'issue#36_broken_constraint' of https://github.com/schakrava/rockstor-core into schakrava-issue#36_broken_constraint

Conflicts:
	src/rockstor/storageadmin/views/share.py