Fix reference in setup.py to salve.util package

This is a reference to a no longer existing package, and therefore must be
discarded.
Moved most of setup tooling out of /setup/ dir

The Makefile and requirements are still there, lest they be mistaken for
requirements of the project itself. This allows users to download and install
by running on the setup.py file. Also separated build and upload setps in
Makefile.
Bumped version to 2.3.1
Merge branch 'bugfix/setuptools-fixes' into dev