sonata_admin_model and the select2 refresh issue

This should fix the wrong jquery cibling and correct the select2  option refresh with the the added entity 
"field_container_" is the correct prefix to perform the 
jQuery('#field_container_{{ id }}').replaceWith(html);
Merge pull request #343 from ghaliano/master

fix sonata_admin_model and the select2 refresh issue
remove duplicate requirements
provide virtual package

This virtual package will be required by libraries that need an
implementation of it but don't want to force one in particular.
Merge pull request #349 from greg0ire/dependency_management_improvements

Dependency management improvements
Merge remote-tracking branch 'sonata-project/master'

Conflicts:
	composer.json