REP-234 NPE from missing system properties

THIS BECAME MESSY.

The change I made should prevent the servlet from executing if certain system properties are not provided (either on the command line or through a container's domain configuration file).

I left a functional test in here that won't work right now. We could extend the functionality of our test framework to maybe get it working, but that's outside the scope of this story. Let me know if this should be removed.

I considered refactoring the log messages and exception bit, but since that code is only replicated twice, I decided not to pre-optimize. It's not the cleanest thing, but it should work.

Note that this change will need to be manually tested.