Redact client_id, client_secret from Octokit::Error

Add redact_url method to redact things, don't show credentials in error logs

Refs #341
Update redact_url to remove formatting

method shouldn't add the formatting.
Merge pull request #342 from catsby/redact_client_things

Redact client_id, client_secret from Octokit::Error
v2.6.1
Release 2.6.1