pool: Port xrootd and http movers to thread-less architecture

Benefits:

- Get rid of idle thread per transfer problem

- Make protocol specific configuration much cleaner

- Have per pool Netty instances and thread pools rather than
  per domain

The last point is important to note as it means that xrootdMoverXXX and
httpMoverXXX properties are now interpreted per pool, and not per
domain.

For xrootd I also cleaned up the redirect handling. The pool now
send a single socket address to the door, and backwards compatibility
with pools older than 2.5 years has been dropped (don't know the
exact version number but dCache's that old are not supported anymore).

Target: trunk
Require-book: yes
Require-notes: yes
Acked-by: Tigran Mkrtchyan <tigran.mkrtchyan@desy.de>
Patch: http://rb.dcache.org/r/5448/