Older versions of the MySQL / MariaDB driver do not support the same level of granular SSL/TLS control, and the legacy "useSSL" parameter cannot be specified without breaking the behavior of "sslMode".

The improvements from commit ed7e7bbb were supposed to go to `staging/1.2.0` and then get merged back to `master`, not directly to `master`. The same changes are now being redone against `staging/1.2.0` (to be merged back in again) so that things can be put back in proper sync.

GUACAMOLE-103: Use UriBuilder for syntax-aware URL construction, rather than simple String concatenation.

Exception handling within the SAML extension has been updated such that
exceptions generate a Guacamole Error rather than a username/password
login.  Tokens now are canonicalized with a standard prefix.  Now using
an Iterator to handle SAMLResponseMap cleanup.

Includes implementation of executor shutdown, and correctly removing
items from the shared response map.

GUACAMOLE-103: Merge extension API support for redirection during authentication/authorization process.