Fix for OPENAM-2787 - review: CR-2187
This one turned out to be an issue with the modifyRoleMembership
implementation: instead of modifying the user entries to have the nsRoleDN
attribute, it was incorrectly setting the member DNs on the role entry.
New tests have been incorporated to cover this scenario.

git-svn-id: https://svn.forgerock.org/openam/trunk/openam@6308 0f4defcf-c51a-4c67-9f44-6fb5eba73c5d