Added a catch all for Fatal Server Exceptions.

- We need to put this through something like airbrake but for now our syslog aggregator emails should work
use dea.shutdown to invalidate advertisements

this solves the homer simpson problem of evacuating an app to the same
DEA it was on

[finishes #50233251]
Add ServiceInstance's dashboard_url to the app_summary endpoint
unregister routes when shutting down

[finishes #50333517]