Use browserify

[YerkoPalma]

What do you think about using browserify in this project? This change would have some advantages:

• Allow to require the widget: because generally front end projects using npm don't access to node_modules, they require modules to work with other modules. Also you might easily convert this to a React component, virtual dom, etc.
• Improve the build process, in the same file include UMD build, for the cdn. Also add source maps for the minified file.
• Take advantage of other packages, like babel to use template strings (related #7) instead of including a whole library.

If you agree, I can send a PR later :+1:

[surbhioberoi]

Sure @YerkoPalma I am still learning about build processes, a PR would be helpful.