cells: Associate threads and initialization messages with their cell

Use the cell name in threads. Do more cell initialization in
a thread associated with the cell, thus directing log messages
to the proper pinboard.

Target: trunk
Require-notes: no
Require-book: no
Acked-by: Paul Millar <paul.millar@desy.de>
Patch: http://rb.dcache.org/r/6282/