Add PanicKit support

[grrrrr]

It would be really useful to have PanicKit support added to the edReader app

This would allow the user to trigger (e.g. with Ripple) a destructive or non destructive response in a "panic" situation where a device may be at risk of being taken. Given the nature of some of the subs on Reddit this could reduce the potential for persecution in some repressive countries or just simple embarrassment for others.

More details on PanicKit: https://guardianproject.info/code/panickit/