CRM-14399 add alterCalculatedMembershipStatus hook

Conflicts:
	api/v3/MembershipStatus.php
CRM-14399 one more call to getMembershipStatusByDate + update add function call to be more standard
Merge pull request #2785 from eileenmcnaughton/CRM-14399-master

CRM-14399 add alterCalculatedMembershipStatus hook