Exit on critical config misses

* If session secret or db connect errors, die.
Remove device if erased.

* page refresh required before UI will no longer show current device
Merge branch 'dev' of github.com:mozilla-services/FindMyDevice into dev
Merge pull request #236 from jrconlin/dev

Issue #232; #235
Changing runserver to runserver.bash
tweaked sql/README.md with some formatting and fixed typo in file path
Merge pull request #240 from pdehaan/runserver_bashing

Changing runserver to runserver.bash
Merge branch 'dev' into functional-test-madness
Changed erase handling to be more like the real device.

https://github.com/mozilla-b2g/gaia/blob/0a0f549c6b341b8b14c4188390abbefe52847cb4/apps/findmydevice/js/commands.js#L194