Use timestamp in loopingcall

All time related data in loopingcall are in seconds.
Therefore creating datetime objects only adds overhead to the module.
This patch replaces all datetime objects with utc timestamps in loopingcall.

The rational of using timeutils was disscussed here,
https://review.openstack.org/#/c/16310/1..5/openstack/common/loopingcall.py,cm
which was to use set_time_override to avoid actual time delays in test scripts.
Now that set_time_override is deprecated, we no longer need to use timeutils.

A lambda function returning time.time() was declared due to mock collisions
with time.time() called in the logging module.
Changes to test scripts were made accordingly.

Change-Id: I38749f3c7bfff23164481b2341d56154ba737765
Changes calcuation of variable delay

In the loopingcall.FixedIntervalLoopingCall class, an warning is logged
when 'delay' is equal or less than zero. Commonly delayed time is
considered something over due from a deadline which is a positive value.

Also a task delayed zero seconds is not considered delayed
but finished on time.

Therefore this patch fixes the calculation of the variable 'delay' and
omits a warning log when 'delay' is zero

Change-Id: I9dbae0838e6c03fa0eaa79e7332e650b02ed9c77
update new requests logger to default WARN

The requests library changed the name of their logger, so now
the terrible logging is back in all the projects. Set the new
logger level to WARN as well as the old name.

Change-Id: Ifbc22d097952cae4537fd97a96985bbb42c1b76c
Mark gettextutils obsolete

The first version of oslo.i18n has been released, so we can mark
gettextutils as obsolete.

Change-Id: I56ea6ecc2cba5f3b4614189bbfa366efff29e50e
Merge "Use timestamp in loopingcall"
Merge "update new requests logger to default WARN"
Merge "Changes calcuation of variable delay"
Allow test_service to run in isolation

While trying to port oslo to python 3, we discovered that test_service
wasn't working when not run with testr. SIGHUP tests expect processes to
be a daemon, which is not the case when run directly in process. The fix
can be tested running:

$ python -m openstack.common.lockutils python -m testtools.run \
  tests.unit.test_service

Change-Id: Ie45813668e658789cc133387fce7cd643ec42bb1