CRM-13034 Fix formRule in Main.php to ensure that premium minimum req amount is checked regardless of whether contribution page contains a quick config amount_block OR has membership block or a price set.

----------------------------------------
* CRM-13034: Premium minimum price isn't checked if Amounts Block is deselected
  http://issues.civicrm.org/jira/browse/CRM-13034
Merge pull request #1191 from davecivicrm/CRM-13034

CRM-13034 Fix formRule in Main.php to ensure that premium minimum req am...