Retrieve repository directly.
JENKINS-13726: Github plugin should work with Guthub enterprise by allowing for overriding the github URL.
follow-up fix and documenting the expected value
massaging this a bit to accept the full URL
turns out we never exposed the ability to specify the custom URL.

So no backward compatibility provision is needed.
Also in this change, I stopped exposin the password. See the code comment for more details
Merge branch 'pull-22'
oops test failures
[maven-release-plugin] prepare release github-api-1.34
[maven-release-plugin] prepare for next development iteration
Removed last traces of web client.
Removed proprietary api usage.
Merge pull request #26 from johnou/remove-webclient

Removed web client and proprietary api usage.
Password is no longer required for api usage.
Fix base64 encoding.
Merge pull request #27 from johnou/deprecated-password

Password is no longer required for api usage and fix for broken base64 encoding.
Added membership checks.
Refactored test.
follow up fix to the pull request #28
adding OAuth support in ~/.github
switching to Markdown