Maintenance for this project

[indexzero]

This PR does the following:

• Includes PRs that should be merged: Quote every non color string #14, Catch JSON.parse error #11, Add repository field to package.json #4
• Supercedes other PRs (with similar fixes in different commits): Correct json example in readme #12, Fix convertJs export #6
• Moves to npm run from Makefile
• Updates to the latest conventions with babel using new sub-packages babel-cli and babel-polyfill
• Do not run npm test on npm install

[indexzero]

For all those consuming this downstream this has been published as json-sass-vars until this PR is merged. That package will be deprecated once the next version of json-sass is released.