"Owner" is the name GitHub uses in its API to reference the owner of a
repository. "User" is not correct when the owner is an organization.
This removes some confusion I've encountered over how to configure the
resource while maintaining backwards compatibility.
* fix some err checks
* github api url can be configured (e.g. point it at an enterprise instance)
[finishes #89638752#89633744]
Signed-off-by: Chris Brown <cbrown@pivotal.io>
