Browserify and some refactor

There are many changes in here, and I'm still working on this. The list of changes:
* Default Grunt task is not anymore pushing changes to gh-pages. For that use task build-pages
* Not uglifing D3 as it was taking a lot of time (and many other things removed in grunt refactor)
* Added a copy of unminified pathvisiojs file into dist
* Updated svg-pan-zoom with proposed patch 
* Added demos folder with only html files
* Updated some node modules
* Added new Grunt task for building with browserify (some refactoring, broken tests now are even more broken)
* Browserified the whole app 
* Added notifications plugin
* Added namespaced events
* Fully refactored application entry point

Things I plan to do next:
* Move typeahead, svg-pan-zoom and info-box into plugins
* Add more events 
* Replace d3 with a more suitable library
* Run 2 instances of similar graphs on one page (for this all IDs should be unique on a page)

There are many other things to do, but this is a minimal viable product we can start with.