Merge branch 'master' into 'master'

let setuptools determine the base install path on OSX

This is the last commit from me before the 0.4.0 release.  Its ready to go!

A gentle reminder:
* sign the tag: `git tag -s 0.4.0 -m "tagging release 0.4.0"`
* release tags are `0.4.0` format, not `v0.4.0`
* change the version in `setup.py` to match the tag exactly, char by char

Then I'll post the update to pypi.python.org

See merge request !59