Deprecate subclasses of HashedCredentialsMatcher and cleanup Hash implementations

Per mailing list discussion, the HashedCredentialsMatcher does not need to be abstract and its subclasses should be deprecated (and later removed in 2.0). The Hash implementation subclasses may or may not work the same way based on dev team consensus. Adding this issue to have a number to track against when committing changes performed earlier as a result of SHIRO-186.

Note that these changes should be 100% backwards compatible.