Unify connection retry behavior across drivers

[Federico Ceratto]

Some Tooz drivers can handle configuration options for connection/command retry.
The interface is not consistent across drivers, e.g. Kazoo can handle a keyword argument connection_retry=KazooRetry()

Ideally, the default values should be the safest (e.g. retry connections forever)

[Ben Nemec (bnemec)]

Unfortunately the kazoo case is directly exposing the underlying driver interface. I don't know that that's a pattern we want to repeat, but some sort of common retry configuration does seem reasonable.