Fix create and user-role-add in LDAP backend

The LDAP backend while generating 'dn' for ldapadd operations
does not add the id attribute in the attributes list
While newer versions of LDAP server support this operatoin,
older ones reported error. Eg. OpenLDAP 2.3

This change set fixes that error by adding the required
attribute in the list to make it compatible with older
LDAP versions

Change-Id: I1ed3f53d325eb280e036fbbf8e83d2e645db53cd
Closes-Bug: #1340041
Merge "Fix create and user-role-add in LDAP backend"