Verify next-available limit timestamps are isotime

We format these timestamps using timeutils.isotime() in the limits
view builder, so we should check that in the API sample tests rather
than using the generic timestamp regexp.

Full context here:

  http://lists.openstack.org/pipermail/openstack-dev/2014-April/033971.html

Change-Id: I14bf2eccec38f271eec8d97e8dca6d46f9d93cb3
Verify created_at cloudpipe timestamp is isotime

We format these timestamps using timeutils.isotime() in the cloudpipe
API extension, so we should check that in the API sample tests rather
than using the generic timestamp regexp.

Full context here:

  http://lists.openstack.org/pipermail/openstack-dev/2014-April/033971.html

Change-Id: I52543f68a512da4064a905e2efa453425ce36dae
Use datetime object for stub created_at timestamp

The stubbed out volumes methods returns a volume object with a
pre-serialized datetime object which doesn't give us the opportunity
to test the serialization code properly. Use a real object instead.

Full context here:

  http://lists.openstack.org/pipermail/openstack-dev/2014-April/033971.html

Change-Id: Ie54a3deaf1c32f3e57d03737e9ea1e9dd66a98d8
Use datetime object for fake network timestamps

The fake networks use a pre-serialized timestamp in str(datetime)
format which which doesn't give us the opportunity to test the
serialization code properly and isn't the format use in practice.

Use real dateime objects instead.

Full context here:

  http://lists.openstack.org/pipermail/openstack-dev/2014-April/033971.html

Change-Id: I5cbe722fb59cdd326b4c75dcfea14f206d71f668
Merge "Verify next-available limit timestamps are isotime"
Merge "Verify created_at cloudpipe timestamp is isotime"
Merge "Use datetime object for stub created_at timestamp"
Merge "Use datetime object for fake network timestamps"