Ensure UF Join for Volunteer Sign-up in Upgrade

After creating the new default sign-up profile, ensure that there is an UF Join entry for each volunteer project. Probably unecessary to confirm that there is no joing, as none are expected to exist in the case of an upgrade. This step is not necessary for an install... it is handled upon volunteer project creation.

This is the profile to use:
civicrm_api3('UFGroup', 'getvalue', array('name' => 'volunteer_sign_up', 'return' => 'id'));