Fix URLs rendered by MultiContentSearchWidget

Drop the override of the display_template, since the only difference
between the override and the superclass at:

plone.formwidget.contenttree.widget.MultiContentTreeWidget

Was the override was rendering physical paths instead of  proper URLs
in the href of the related item.
Merge pull request #24 from simplesconsultoria/master

Fix URLs rendered by MultiContentSearchWidget in display mode