Switch to use Brunch for assets compilation.

Brunch replaces Makefile, watch and all r.js in assets compilation
process. It should be more extensible and cleaner than Makefile
approach.
Proper CHANGELOG.
New partial implementation of basic layout (header, footer).
Responsive top bar implementation.

This make the top bar behaves and looks similar to Bootstrap navbar
on mobile responsive level. For mobile layout, the top bar will be
collapsed with toggle icon visible on left side. It is shown in
horizontal for desktop layout.