Use sqlite db on file for unit tests

Use sqlite db on file for unit tests

bug 1054387

So far unit tests were executed using an in-memory database.
Memory was not being freed thus causing oom frequently due to
the increased number of unit tests.
Since sqlite in memory db do not work very well anyway with nose,
we are moving to file-based databases; slower, but safer.

Also, this patch removes a bunch of unit tests which do not add
anything to code coverage or number or test cases exercised.

Change-Id: Ib853727a5268643fbe8a99f6ebd0fc10aca6a43a