Add `FacilityGroup.description` field.
Modify the templates to add it with the group name for the hover text of the group link like manage and coach group.
Initial refactor of unit test.
This fixes the `password should be at least 6 characters` issue when running tests.
Some PEP-8 fixes.
Merge branch 'nalanda-rct2' into feature/1966-Add-group-description

Conflicts:
	kalite/control_panel/templates/control_panel/facility_management.html
	kalite/facility/forms.py
	kalite/facility/tests/form_tests.py
Reassign error message to empty string because the `BaseException.message` has been deprecated in Python 2.6.
Merge update from `nalanda-rct2` branch re use of quotes on url.
Merge pull request #2113 from cpauya/feature/1966-Add-group-description

Add `FacilityGroup.description` field.