Remove dependency of test_v1_api on other tests

test_v1_api would fail if run by itself. A config value was
apparently being set by another test so that this test would
pass if run as part of the whole suite but not alone.

Specifically, the missing value was 'backend' in group 'database'.

This patch imports the 'backend' option in base.py which is the
base of test_v1_api.

Change-Id: I37d72398050057def6a378e03c14a9a4eeb55a16
Closes-bug: #1283242
Removes use of timeutils.set_time_override

The set_time_override function in timeutils was written as a
helper function to mock utcnow for unittests before 'mock' was
generally used. Now that we have mock and fixture, we no longer
need to use it.

Change-Id: I203f7369943b948e0462becbddcba65b2d1576f0
Partial-Bug: #1266962
Merge "Removes use of timeutils.set_time_override"
Merge "Remove dependency of test_v1_api on other tests"