Security upgrade of core and date module

Update Drupal Core to 7.30 and Date module to 2.8.
Related release notes available here:
https://www.drupal.org/drupal-7.30-release-notes
https://www.drupal.org/node/231188

Change-Id: Ia2d04322fff4bc1f49e8cccada2ac2b267a3f9ca