Add missing file type to `.gitattributes`.
Use `node` instead of deprecated `stable` version specifier for Travis.
Set dev tool to `cheap-module-source-map`.
Tracking the version under one `-prerelease` channel allows other packages to depend on `^0.1.0-prerelease` for the most up to date version.
Track the git sha for the release in package.json
Reuse the json package needed for writing the sha to retrieve the package.json version field
