[DO NOT MERGE] fix bug 1075700 - add crypto pass-through crash store

r? @lars - @peterbe and @lonnen should look too if you have time.

Putting up for review/discussion, but please don't merge yet pending some further investigation of the ```simple-crypt``` package being used here.
since the benchmarking crashstore uses the key "wrapped_crashstore", so  if you ever want to  use both benchmarking and encryption, that name will collide in the namespace.  "encrypted_crashstore" would be an appropriate non-colliding alternate name.