ImportErrors are no longer fatal so the setup can bootstrap itself

I do print out a message though for diagnostic purposes.  I don't
like this approach because I like good clear diagnostic messages
when things go wrong that point users in the right direction.  To do
that in this case, I'd really need to figure out what stage of
the build process I'm in to realize if this is really an error
or if it will eventually be resolved via setup_requires.  I haven't
done that (yet?).