[MERGE] Add send format registry, pt 2

[Ian Clatworthy]

Ian Clatworthy has voted tweak.
Status is now: Conditionally approved
Comment:
Looks good. Just check for unnecessary imports at the top of send.py. At 
a minimum, you don't need to import the stuff from bzrlib.command and 
bzrlib.option.

For details, see: 
http://bundlebuggy.aaronbentley.com/project/bzr/request/%3C20090526142255.GA24787%40vernstok.nl%3E
Project: Bazaar