Adjustment of version numbers for nightly releases

[lhstrh]

Fixes #170. To be merged on the day that v0.9.0 is published.

[petervdonovan]

This looks like it should work. I took a quick look at these steps that npm version does:

1. Check to make sure the git working directory is clean before we get started. Your scripts may add files to the commit in future steps. This step is skipped if the --force flag is set.
   2. Run the preversion script. These scripts have access to the old version in package.json. A typical use would be running your full test suite before deploying. Any files you want added to the commit should be explicitly added using git add.
   3. Bump version in package.json as requested (patch, minor, major, etc).
   4. Run the version script. These scripts have access to the new version in package.json (so they can incorporate it into file headers in generated files for example). Again, scripts should explicitly add generated files to the commit using git add.
   5. Commit and tag.
   6. Run the postversion script. Use it to clean up the file system or automatically push the commit and/or tag.

And I think it's true that we were not making important use of any of them.