bozo: bosserver -pidfiles option

bozo: bosserver -pidfiles option

Add an option to bosserver to create pidfiles for long running
processes for simple, fs, and dafs bnode types, as well as the
bosserver process. The pidfiles are located in the server local
directory by default, or in the path specifed by the -pidfiles
command-line option.

Change-Id: I3e85b027dc6f630965f84b18b7f849ac481dabe2
Reviewed-on: http://gerrit.openafs.org/5497
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>