CRM-15366 - Gift Membership Bug Fixes

https://issues.civicrm.org/jira/browse/CRM-15366
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Patch also includes Notices Fixes for
Notice: Undefined property: CRM_Member_Form_Membership::$_values in CRM_Contribute_Form_Contribution_Confirm::processContribution() (line 1186 of /home/web/src/civicrm/CRM/Contribute/Form/Contribution/Confirm.php).
Notice: Undefined property: CRM_Member_Form_Membership::$_membershipBlock in CRM_Contribute_Form_Contribution_Confirm::processRecurringContribution() (line 1461 of /home/web/src/civicrm/CRM/Contribute/Form/Contribution/Confirm.php).
 Notice: Undefined property: CRM_Member_Form_Membership::$_values in CRM_Contribute_Form_Contribution_Confirm::processContribution() (line 1275 of /home/web/src/civicrm/CRM/Contribute/Form/Contribution/Confirm.php).