Consular should quit if it fails to start up

[JayH5]

Due to a Puppet misconfiguration, we recently ran Consular like this:

consular --host= --sync-interval=300 --purge --registration-id=prd-unicore-controller01 --consul=http://:8500 --marathon=http://:8080

Which simply fails to connect to Marathon:

Log opened.
ConsularSite starting on 7001
Starting factory <consular.main.ConsularSite instance at 0x7f5b76741758>
Unhandled error in Deferred:
Unhandled Error
    Traceback (most recent call last):
    Failure: twisted.internet.error.ConnectionRefusedError: Connection was refused by other side: 111: Connection refused.

Consular event callback registered.
Not handling event type: subscribe_event

And then... nothing.

Consular should quit and not appear to things to be happily running.