Updated to JSAPI v3.9 and getting Bootstrap Map files from GitHub repo

Generator now gets the Bootstrap Map css/image/js files directly from GitHub so the files are always up to date.
Removed local copies of those files.
Moved clearBaseMap() function into app.js since it is not included in the latest bootstrapmap.js.
I used `grunt deploy` to push to my repo, so you can see output here: http://tomwayson.github.io/yo-bootmap/