Feat/drag drop

For now, the ng-sortable dependency is added to bower. When installing the lib, bower also install ng-sortable. To make table-settings columns draggable, the developer will need to include the lib.

The bonita.settings is not explicitly requiring ui.sortable to allow using the module whitout sortable columns.

I wondering what the best approach to bundle bonita-js-component (with or without ng-sortable).

poke @velcrin @julien-reboul @dhoko