Fix handling of large number of volumes

o ensure only a maximum of 255 volumes is returned
o ensure the reply with the volume list fits in a certain buffer
  size, testing with 10.8.4 saw the maximum size the client would
  accept to be ~4600 bytes

Fixes bug #527
New configure option --with-tdb
Merge remote-tracking branch 'origin/branch-netatalk-3-0' into develop

Conflicts:
	configure.ac
	libatalk/Makefile.am