Pr 77 link check improvements

[domguinard]

Improving on #77 (but I could not push to this branch as it is coming from a fork).

[ilkedemir]

I did not add the SBR API check as I was not sure if we should handle a response like Cannot GET /api/v1 and {"error":"Subsystem token required","code":"SUBSYSTEM_TOKEN_MISSING"} as it is not clear whether the API is really nonexistent or the request is invalid, or whether we should treat them the same.

Also it seems you removed the issue creation, which is fine.