Added a filter for parts of the version
Using a filter causes a PicklingError on my mac. Test if this is the case on Buildbot.
Any custom filter causes a PicklingError, I want to see if this is a Mac enchant issue
Filter module
Filter module and working filter for version
Removed useless import and test
Removed quotes around version
Add some words so tox sphinx passes for me personally.
Some cleanups based on review comments.
Merge pull request #741 from ClusterHQ/version-substitution-724

Versions are no longer spellchecked.

Fixes #724.