fixes Bug 636868:  support for json dump from new MDSW

this is a big, but incremental change to the processor.  It adds support for a version of MDSW that emits both pipe dump (pDump) and json dump (jDump).  The json version of the dump becomes is added to the processed_crash json as the key `json_dump`.  The pipe dump remains with the key `dump`.  

The two systems are supported in parallel so that the transition can be as painless as possible.  

Due to time constraints, I've had very little opportunity to test beyond the unit tests.  The new MDSW wasn't delivered to me until the final hour before my vacation.  I don't know if someone wants to take over the responsibility for this or if it will bit rot during my absence.