Moving pwclient into its own project

[Stephen Finucane]

I'd like to move pwclient into its own project/repo/possibly mailing
list. There are a couple of reasons for doing this:

- I want to be able to package this up for PyPi to allow installation
  with pip
- I want to be able to release new pwclient features to everyone
  without waiting for their patchwork admin to bump the Patchwork
  version
- I want to be able to provide more comprehensive documentation for
  pwclient, as it slowly morphs into a VCS-independent, general-purpose
  Patchwork CLI tool
- (stretch goal) I'd like to create deb/rpm packages for Fedora,
  Ubuntu, etc.

I've already taken this approach for git-pw [1], which I'll move into
the getpatchwork namespace soonish and which I'm hoping will replace
pwclient's 'am' subcommand with something a little more flexible. Does
anyone see any reason /not/ to do this for pwclient?

Cheers,
Stephen

[1] https://github.com/stephenfin/git-pw