AngularJS pages do not display dates in server's timezone

[Kristine Bujold]

Brief Description
-----------------
Horizon's AngularJS pages (for example Images) does not display timestamp in the server's timezone. The timezone used is the browser's.

Steps to Reproduce
------------------
- If Timezone is not set under Settings (menu on the top right):
Set the server's system timezone to a one different from UTC and the browser.
The Image timestamps (for example 'Created At') are displayed in the browser's timezone and not the server's timezone.

or

- If Timezone is set under Settings (menu on the top right):
Set Horizon's Settings Timezone to one that is different from UTC and the browser.
The Image timestamps (for example 'Created At') are displayed in the browser's timezone and not the Settings' timezone.

Expected Behavior
------------------
AngularJS pages should align with Django pages which use the timezone from the Horizon's cookie (which is set under the Settings menu on the top right), or if that is not set use the server's timezone.

Actual Behavior
----------------
The AngularJS pages use the browser's timezone.

Reproducibility
---------------
Reproducible