Provide faceted search configuration for target Platform 5.6 + documentation

(Note: this issue is actually related to the "Studio" project)

Original report is here: http://answers.nuxeo.com/questions/6527/cant-save-search-due-to-unknown-type-faceted_search_default_cv

The problem is that content views with the "Faceted search" checkbox enabled are contributed with code like:

<doctype name="faceted_search_default_cv" extends="FacetedSearch">
<facet name="FacetedSearch"/>
<facet name="HiddenInNavigation"/>
<schema name="faceted_search_default_cv"/>
</doctype>

Since the XML refers to FacetedSearch which is declared nowhere, the doctype registration is postponed until after the SQL Model is initialized. As a consequence, no persistence of these types is possible, thus breaking the ability to save searches.

This can be fixed by declaring the FacetedSearch facet:

<extension point="doctype" target="org.nuxeo.ecm.core.schema.TypeService">
<facet name="FacetedSearch" />
</extension>