Require tenant to be set

For my application, I wanted tenant to be set at all times - if it wasn't, I wanted an exception raised.  To that end, I initially created commit 09bcf587c5c467d71fd8229ccf26b86a3148f8d7 for my own use.  I realized recently that others might be interested in this functionality as well, so I figured I'd turn it into an option to be set, allowing both the current functionality as well as use of this more limited functionality.

I also wrote some basic tests to verify its use.

Please let me know if this isn't the best way to go about accomplishing this, or if there is other work you would like completed before doing a pull request.