Make sysadmin dashboard gitlog date timezone-aware

@carsongee Just a small change to the sysadmin dashboard gitlog:
* Redundancy reduced in the template
* Date is timezone aware and formatted as `util.date_utils.DEFAULT_DATE_TIME_FORMAT`

Before:
-----------
![before](http://i.imgur.com/71heogf.png)

After:
--------
![after](http://i.imgur.com/GnBQvzQ.png)


Do you need to reset these things at the end of the test? Ideally, the class should define a `tearDown` method that resets the system back to the same state after every test. If the system is in a different state after running this test, then we'll run into test isolation issues.