Complete backend update of latest ionic SASS release

[pbernasconi]

Every time the app is run, it should check to verify if the latest version of the Ionic SASS files are inside the /server/ionic/. The latest version should be stored somewhere (perhaps a .json) file, or maybe in the Mongo DB, but might be overkill.

If the official Ionic SASS files are ahead/newer than those in the ionic theme editor, download each file and update the local version.

This will require semantic version comparatives: https://github.com/npm/node-semver