Merge branch 'master' into 'master'

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