Fast rebuilding of bundles using watchify
Add versioning of files based on their contents.

Renames file to include a portion of their md5sum in their filename.

e.g. home.js -> home.88d85647.js
Creates a rev-manifest.json with the mappings of old to new filenames
Add task for compiling sass files into CSS.

gulp-rev-all will version css and image files as well, and rename urls
inside the generated CSS files to point to the versioned images
Add concatenation, minification and versioning of vendor CSS files