Fix #40 - LDAP user/pass not saving

LDAP username & password settings did not seem to be saving to
the database. Added those two fields to the retrieval of
settings (they were missing), but didn't find the save code
before it started working. Jonathan set me up with dev access
to the database at that time, so I'm thinking that something
happened with the DB permissions.
Merge branch 'dev' of https://github.com/BellevueCollege/wordpress-cas-client into issue-40

Conflicts:
	wordpress-cas-client.php

Merged my changes with recent changes made by other developer.
Merge pull request #42 from shawn-bellevuecollege/issue-40

Merge changes fix "LDAP User" and "LDAP Password" fields being saved in
single site installations. This problem does not show up in multisite
installations.

Additionally a new bug under single site installations was discovered
where "CAS Server URI" and "LDAP URI" fields are not being saved. This
bug will be filed separately.