New Cache Package

This is **not** ready to be merged, but I wanted to start the conversation about how we dramatically simplify the caching package for Joomla.  The existing system is entirely too complex and doesn't honor the principle of separation of concerns.  Hopefully this can serve as a starting point for us to figure out what caching looks like for Joomla in the longer term.  As with everything these days I'm striving for simple, clear and concise.