Update to version 0.4.0

Note that we are no longer using `devN` in the version numbering. This
is in accordance with [PEP0440][pep] which states that:

> While they may be useful for continuous integration purposes,
> publishing developmental releases of pre-releases to general purpose
> public index servers is strongly discouraged, as it makes the version
> identifier difficult to parse for human readers. If such a release
> needs to be published, it is substantially clearer to instead create a
> new pre-release by incrementing the numeric component.

[pep]: https://www.python.org/dev/peps/pep-0440/#developmental-releases

This version is the first to have docs online at https:/readthedocs.org.

CHANGELOG.md

@@ -5,6 +5,8 @@ All notable changes to this project will be documented in this file.
 This project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
+
+## v0.4.0
 ### Added
 - This CHANGELOG file!
 - Docs are now up on [readthedocs][rtd].

datascience/version.py

@@ -1 +1 @@
-__version__ = '0.3.dev22'
+__version__ = '0.4.0'