Updates to the Python/GitPackagingPQ wiki page

[Edward Betts <edward@4angle.com>]

Hello from the mini-DebConf in Hambug.

I've made some improvements to the Python packaging with gbp-pq wiki page.

https://wiki.debian.org/Python/GitPackagingPQ

I've replaced all the references to alioth with instructions for Salsa.

Feel free to revert or correct any of my changes that you think are wrong.

The page still needs some more work so it covers both the packaging of modules
and applications. Currently the examples are all for packaging modules.
-- 
Edward.