Convert steal plugin to use CommonJS

Previously was using ES6 which won't work in Phantom due to Traceur
using ES5 features that Phantom 1.x doesn't support. This switches the
plugin to use CommonJS, matching what css.js uses.
Remove distPath logic

This commit purges all distPath logic, going to use System.paths instead
to point to the bundle locations, will do this as part of the build in
steal-tools.
Set System.paths for bundles in production

When the env === "production", set up the default bundles paths so that
they will be found in their dist directory.
Merge pull request #204 from bitovi/dist-path-purge

Fix lookup for production bundles
Merge pull request #202 from bitovi/less-cjs

Make less.js use syntax other than ES6
Add support for lessOptions.