Change Debug to Verbose Logging

I learned this lesson with the TinyMCE module... getting MERCI to a release candidate that non-developers can use without creating a constant stream of issues will require a debug function that writes human readable messages to the log. When a user creates a reservation for item X from Y to Z and MERCI returns a conflict or allows a reservation the user thought should be denied, they need to be able to turn on debug and see each validation check. This becomes even more important when custom modules can override a specific validation check. I've started this, but it needs work.