Remove HTML generation from container_block plugin
It now uses BoxesHelper logic instead of HTML generation within the model violating MVC.
As it is a class within a module
BoxesHelper required fixes to
handle the module prefix when searching for the proper view to render.
Previously it would wrongly search for
blocks/container_block_plugin/container.html.erb instead of
In case gitlab build does not start, here is the Travis build: https://travis-ci.org/rafamanzo/noosfero/builds/118607978