[PEAK] Upgrading required Python version

[Ty Sarna]

> Hi all.  I'm thinking about bumping the version of Python required for 
> PyProtocols and PEAK.  Does anybody besides me actually still use 
> 2.2?  And, would anyone see a problem upgrading to 2.4?

I'm +1 (for large values of 1) on dropping 2.2 support, and maybe +0.75
on dropping 2.3. Personally I've mostly switched to 2.4 and would love
to be able to start using the decorator syntax and such, as long as it
isn't going to hurt anyone else.