Use a blacklist of forbidden psycopg2 versions instead of a whitelist

Just assume future psycopg2 versions will be compatible with the zope adapter:
if a bug is discovered the incompatible list can be updated, but if the
projects are disjoint we cannot just release a new zope adapter at each
psycopg version.
Added some useful links in the readme
Bumped to release 2.4.6