Change the way last modified time is displayed for the Swift object

[Ashish Chandra]

While displaying last modified time we get "x-timestamp" for an object and then we convert it to Human readable format, which can be done effieciently using "last-modified" value returned, and simply using it.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/95150

[Ashish Chandra (ashish-chandra)]

Fix proposed to branch: master
Review: https://review.openstack.org/95150

[OpenStack Infra (hudson-openstack)]

Change abandoned by David Lyle (<email address hidden>) on branch: master
Review: https://review.openstack.org/95150
Reason: This review is > 4 weeks without comment, and failed Jenkins the last time it was checked. We are abandoning this for now. Feel free to reactivate the review by pressing the restore button and leaving a 'recheck' comment to get fresh test results.

[Rob Cresswell (robcresswell-deactivatedaccount)]

Given that the old Swift view has been deprecated and we have low bandwidth for bugfixes, I'm closing non-critical bugs in the Python Containers panel.