general: customization support of Bootstrap core with LESS

* added grunt support for copying libraries from bower
* added grunt tasks for production and development
* custom LESS files for Bootstrap customization
* updated README with installation instructions

Signed-off-by: Georgios Kokosioulis <giokokos@gmail.com>
Reviewed-by: Javier Martin Montull <javier.martin.montull@cern.ch>
search: selectable options in the search box

Signed-off-by: Georgios Kokosioulis <giokokos@gmail.com>
Reviewed-by: Javier Martin Montull <javier.martin.montull@cern.ch>