Merge branch 'zz-2013-09-fix_on_delete' into zz-2013-08, ours

Strategy: "ours" (ignored zz-2013-09-fix_on_delete because it is completely
                  in master by parts)
Merged because referenced from github.

important pieces of code of branch "zz-2013-08" are:

can_return_id_from_insert = True
can_use_chunked_reads =
test_db_allows_multiple_connections = False
def _supports_transactions(self):
def _supports_stddev(self):
def __unicode__ ... "If the object has a name"