bozo: retry start after error stops

bozo: retry start after error stops

After a bnode is stopped because of two many consecutive exits
delay for some time and attempt to start the bnode again. Countine
to retry on each error stop, doubling the delay for each retry
attempt until a maxium number of attempts.

Change-Id: Ib6a4935d09c70c69de87f65717562bd3dcde761b
Reviewed-on: http://gerrit.openafs.org/5534
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>