[Distutils] install_recommends proposal

[zooko]

The allmydata.org "Tahoe" project does something similar in a non- 
machine-readable way.  We specify a minimum version if one is known,  
and we also mention specific versions that have been tested and are  
known to work:

http://allmydata.org/trac/tahoe/browser/README

The fact that this kind of practice is common suggests that a machine- 
readable implementation of it might be useful.

Regards,

Zooko