update gulp to 3.6
use watchify for faster browserify builds

https://github.com/gulpjs/gulp/blob/master/docs/recipes/fast-browserify-builds-with-watchify.md
Update README.md
use the same tasks for production & development build

production state is determined with the NODE_ENV variable from this point forwards
store bower components in bower_components directory
Merge branch 'master' into angular