Add usemin tasks, with uglify, concat and cssmin
Add htmlmin
Fix an issue of htmlmin

    This patch fix this issue https://github.com/yeoman/grunt-usemin/issues/44
using @iham's solution:
https://github.com/yeoman/grunt-usemin/issues/44#issuecomment-17430724
Add htmlrefs support

    htmlrefs allows you to change the path for scripts, we will use it for
google cdn script files, it will improve performances for common javascript
libraries. In order to use it in dist target a server is needed, because
the file:// protocol will not handle relative linking.
Move bower_components, make a copy of it in dist
Complete the gruntfile and installation