CRM-17723 Inherited Membership not created from Online Contribution Page

Steps to reproduce :

1) Create a membership type -> Select `Employer of` for Relationship Type.
2) Create a Contribution Page with `is_organisation` checked in Settings tab.
3) Select `On behalf of Organization` for Organization Profile.
4) Enable Membership and select the membership type create in Step 1.
5) Open the live page and Register an Organization filling the `Organisation Details` and `Name and Address` Profile.
6) Membership for the organization gets created, however, the individual created from Name and Address profile dosen't have any membership recorded.

Note: The relationship gets created properly between them.

Encountered in WebTest_Member_OnlineMembershipRenewTest.testUpdateInheritedMembershipOnBehalfOfRenewal