Normalize API extension updated timestamp format

It's unusual to include a '+00:00' offset in an ISO8601 timestamp
rather than just using the 'Z' suffix. It's also very weird for our
API to be returning timestamps which aren't in UTC.

Let's make these timestamps consistent with other timestamps by
using UTC always and representing that with a 'Z' suffix. Also,
enforce this in the API sample tests by using a new 'isotime' regexp.

A small number of the extensions in the API sample templates
specified the exact timestamp, so templatize those before regenerating
the API samples for GET /extensions.

Full context here:

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

Change-Id: Idf429e55e4ae13738ac531a25ce54b20d395410d
Use actual fake timestamp in API templates

The 2011-01-01T01:02:03Z is seen throughout the images API sample
tests because it is hard-coded in the fake image service. In some
of the API templates, we include the timestamp rather than matching
against a regexp but in many we don't. Let's consistently match
against the actual timestamp we know to expect.

Full context here:

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

Change-Id: I727c0aabac0e32b435068c37d535daa8c983364c
Use timeutils.isotime() in images view builder

Rather than using a direct call to strftime() with the same format
as timeutils.isotime() just use isotime() itself.

Full context here:

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

Change-Id: Ifeb9e24566e220f80cf8051ec16b8c868908c642
Merge "Normalize API extension updated timestamp format"
Merge "Use actual fake timestamp in API templates"
Merge "Use timeutils.isotime() in images view builder"