Added new fields to register_settings

Resolved #49 - New fields like casserver, ldapuri were not being saved
since they were not being added to the options list for single site.
Merge pull request #50 from TriptiSharma/issue-49

All fields on the CAS Client form were tested and verified against the database. The only field that is currently on the form that is not being saved is E-mail suffix but that was not part of the task