Use custom narrowly scoped interfaces for client access from the
RollingUpdater and Resizer. This allows for more flexible downstream
integration and unit testing without imposing a burden to implement
the entire client.Interface for just a handful of methods.
When kubectl does rolling updates of replication controllers, retry updates that
fail due to version mismatches (caused by concurrent updates by other clients).
These failed rolling updates were causing intermittent e2e test failures
(e.g. issue 5821)
