Properly handle emulated ldap enablement

Prior to this patch, a member attribute will attempt to be added to the enabled
project even if it already exists. This fails to pass since in LDAP you cannot
have two of the same member attributes in an object.

Change-Id: Ic2373b01eb9921fbf5e9ad828628119288821dba
Fixes: bug #1155234
Merge "Properly handle emulated ldap enablement"