Rename API token to OAuth token.
Update HTML to reference OAuth tokens.
Use oauthAccessToken for consistency with how the API wrapper references it.
Missed a spot.
Don't use the username anymore.
Bump github-api version.
Merge branch 'pull-25'

The change in the Credential change is breaking, but OTOH the API token
has stopped working for a while anyway, so I think this is an OK change.