Fix nova client initialization arguments

We already have token and endpoints in context, so, just pass them to
the nova client.

Change-Id: Ic35e275fd404e83e02b503fa8ee8c1c372885e8b
Remove kombu from requirements

It was added with oslo.rpc half a year ago. We neither need it
now nor in foreseeable future.

Change-Id: Ia45eb58381460a8668ed16031ec3fe47905cea31
Merge "Remove kombu from requirements"
Merge "Fix nova client initialization arguments"