cas 7.x-1.6

This release contains many bug fixes and a few features for both the main CAS module and the CAS Server sub-module.

CAS client module (the main module):
#2223329: Logged In users end up with service tickets in current URL
#2737897: Intermittent fatal MySQL errors upon login
#2799297: Clarify comments in our API file regarding usage of the "name" property in hook_cas_user_alter
#2293193: Remove default CAS server
#2925151: Old CAS login data is never cleared
#2914223: Use format_username() when displaying the user's name
#2845461: Links in README.txt are out of date
#2678256: Position of cas-links above the login button is confusing
#2735027: Bad URL in Recent log messages after creating
#2790179: Document that the Admin Views module is not supported
#2925379: Add requirements check that throws an error/warning when SSL validation is disabled
#2902120: Hash the cas_session_id field to support longer service tickets being stored
#2232805: Visiting login URL containing expired or invalid service ticket results in 500 error

CAS Server sub-module:
#1904914: Too many tickets can cause log out to time out
#2927516: Error when not passing service parameter on logout
#2315593: CAS Server service field size