Suppport roles for authenticate

[kadogo]

It's not very beautiful but it work for me.

I add a new attribute groupSearchUser (role for users).
I assign this to groupsearch and do a groupsearch in the authenticate part.

If someone see a problem feel free to adapt it.

[xerya]

Hi.

In your version, lines 129-130 cause authentication to fail on first try if user is not admin. Session is still set so on next try it succeeds. Personally I changed those lines to

      console.debug('ep_ldapauth.authenticate: user not admin');
      return cb([true]);