Added db upgrade where we update only the existing groupviews blocks where:
1) the group is submittable to
2) no choice has been selected to view submissions

This way we don't accidentially overwrite a user's choice

behatnotneeded

Change-Id: Idd50fe3a75a7434cbbd5ff30d755708c9f855e7b
Signed-off-by: Robert Lyon <robertl@catalyst.net.nz>