Groups working

Need to eradicate magic-strings and create proper fields for the group
base DN.
Add LDAPgroupbaseDN to ldap configuration page

Baby steps for my second day in PERL land.
Use LDAPgroupbaseDN to authenticate user

That was too easy.
Groups are working.

This is a useful commit comment...
Simplify code

This should make things more streamlined. I hope.
Remove magic strings

Exposed LDAPgidattribute: this is the identifier that you want to use
such as cn or gid (in my case). So, a full dn for a group called admin
would be gid=admin,(LDAPbasegroupDN).
Get email via query

Had to add this because emails don't always contain uids.