Ensure distribution files are included in the npm package.

Progress on #6 and #74.
Merge pull request #144 from nicksay/releases-npm

Ensure distribution files are included in the npm package.
Create a release script.

Builds, tags, and pushes a version release based on a given commit.  Releases
are different than regular commits because they will also contain distribution
files in the repository (i.e. the `dist` folder).

Progress on #6 and #74.