Use UTC (London) as the default timezone

:Release Notes:
The default timezone is now set to UTC.

:Detailed Notes:
As there is no generic GMT/UTC timezone, London is selected as the
new default instead of America/Los_Angeles

:Testing Performed:
Launced emulator and checked the image.

:QA Notes:

:Issues Addressed:

Open-webOS-DCO-1.0-Signed-off-by: Keith Derrick <keith.derrick@lge.com>

Change-Id: Ica9e404df9ffee1ed082bd424ce5e7451ea8e19d
Reviewed-on: https://g2g.palm.com/4748
Reviewed-by: DCO Verification
Reviewed-by: Keith Derrick <keith.derrick@lge.com>
Tested-by: Keith Derrick <keith.derrick@lge.com>
Reviewed-by: Gayathri Srinivasan <gayathri.srinivasan@lge.com>
Reviewed-by: Sapna Todwal <sapna.todwal@lge.com>