Fix contact selection jquery and url in relationship create

If a trivial fix, please fix point 1 in 3.0.3

Check: http://forum.civicrm.org/index.php/topic,3467.msg46629.html#msg46629

1. Fix the jQ post url to also send the contact id if we found a match. Fix The relationship search to return only that specific result

2. In 3.1, the jQ autocomplete in relationship (and other places) should use the same url as the quick search in nav bar