Improve support for CAN frames

[whizzosoftware]

CAN (Cancel) frames are not always properly handled within WZWave. This is especially noticeable with certain PC controllers (e.g. Aeotec Z-Stick Gen 5).

I think this problem can be addressed in the following manner:

1. Create WZWave debug logs that demonstrate the problem. For example, a bad log entry might look like "CAN: Received unknown data frame: com.whizzosoftware.wzwave.frame.CAN@52b777a1"

2. Using the raw serial data (or higher level frame objects) from the logs collected in step 1, create failing unit tests that reproduce the problem.

3. Make the unit tests pass :-)