Fixed #23514 -- Prevented queries in PostGISOperations init

Thanks Mattia Procopio for the report.
Fixed #21357 -- Fixed test client session initialization.

The test client will now create a session when it is first accessed
if no session already exists.
Set new oscaro version

I had to tweak django.utils.get_version to make it work
Merge pull request #1 from oscaro/oscaro-1.7-first-backports

django 1.7 "oscaro" first backports