#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.
minor typo fixed
Merge pull request #70 from effhaa/patch-2

Minor Typo in German translation
#7 fix visibility of some of the functions
#7 all validation calls should be public
Merge branch '7_parameter_validation_in_client'
Fix small naming issues and debug infos
#67 add example on how to properly secure the session cookie
#67 fix example text descriptions
#68 allow for multiple server CAS connections with one phpcas client on
one server by adding the CAS server url to the phpcas session cookie
as new variable
#68 add multi server logout() capabilities.
Merge remote-tracking branch 'upstream/master'