Task #2261 - Implement panic functionality

Borrowed some code from the Paik project.

"Wipe entire app" now works, but "Wipe my data" does not. This is because:

1. The app is not terminated like is should. Would be good if someone with a good knowledge of the informaCam lifecycle could have a look as to why =)

2. iWitness.dataWipe() needs to be implemented properly. The commented code did seem to do the job - upon relaunch one was presented with the normal setup workflow. However, after the 6 photos the app then crashed this "second time around". Apparently some stale data still lying around somewhere?