* Handle GitHub "Repository access blocked" error
We've been seeing a lot of these errors on DEV, and it's a pretty
reasonable expectation that if we're being blocked from seeing them
using the user's OAuth access token that this isn't temporary.
* Re-raise so we don't swallow this error
* Constant name != company name???!?!?!
* Registers the Github AcocuntSuspended & RepositoryUnavailable errors
Adds the above-mentioned errors to the list of known errors raised by
Octokit as to make possible for the rest of the application to
specifically trap those.
* Makes the RepoSyncWorker error handling rely on types
The current implementation attempted to parse the error message to
determine if the error reported by Github's API can/should be handled,
this commit changes the implementation so that the exception type is
used instead.
