Update CAS.php

Added a timestamp to the beginning of each stack trace in a debugging session.
Update lib.php

[Fix] Since some usernames from LDAP may be capitalized, comparing them to a lower-case string fails. To do a real comparison it is probably best to use case-insensitive usernames.
Merge pull request #3 from TrinityWestern/master

Make usernames case-insensitive both side