#7 Alternate implementation - Moved parameter validation into the CAS_Client.

Proxied-service tests are currently failing because the tests don't properly
authenticate the user due to older implementations of CAS_Client->_callback()
exiting. Now that it throws a CAS_GracefullTerminationException we should be
able to fully mock the PGT storage process.
# 7 Fixed classname in type-check.
#7 streamlining of exception throwing, new exception classes, few style
corrections, corretion of a couple of logic errors
#7 Move the markAuthenticationCall() call to a different location to
also include all previously authentiated users.
#7 fix visibility of some of the functions
#7 all validation calls should be public
Merge branch '7_parameter_validation_in_client'