[web] Move request handling logic into cubicweb application. (closes #2200684) We improve http status handling in the process: ``application.publish`` have been renamed to ``application.handle`` to better reflect it's roles. The request object gain a status_out attribute to convey the HTTP status of the response. WSGI and etwist code have been updated. Exception gain status attribute

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sync_schema_props_perms('cw_source', syncprops=False)

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if schema['BigInt'].eid is None:

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    add_entity_type('BigInt')