fix case of case name
Make the SLO cache unique per SimpleCAS install

Applications can have multiple auth endpoints, so using the current URL might not be the best solution for scoping.
Support disabling SLO

Have it enabled by default, but allow disabling it.
Scope the cache to the application based on session cookie settings

This should be more reliable than the current URL because there can be multiple authentication endpoints.  It should also be more reliable than the current directory because a library can be shared across applications.