Add overrides for logbook and pyrss2gen

Reported on Twitter by Robert Wall
Various tweaks to README
override ssh cause it is merged back to paramiko
give ssh github url
Run tests on PyPy and Python 3.4
Add guidelines explaining how to add a project to overrides.json
Remove stale overrides
Move logging initialization to main()

Otherwise you get a warning about uninitialized logging since
setuptools creates an entry point that directly calls __main__.main()
instead of using runpy which triggers the right thing under `if
‘__name__’ == ‘__main__’`.
Start v2.1.1 stuff
Normalize direct dependencies

Closes issue #55