When configuring CircleCI, the API token field is required, but this is

only an aspect of the form field. We ended up running into some

situations (particularly in unit testing) where the integration was

configured but the API token was unset. In this case, we'd end up with

bad requests.
This change checks for an empty or missing API token, and preemptively

fails the operation. The error will be logged as well as included in the

status update.

Tested that attempting to start a request with a missing API token

  produced the correct log and error.
Ran unit tests.