[search] Not registered at act stream

We're getting a 500 error upon Search sharing:

Internal Server Error: /platform/api/v1/search/share/anjos/foo_search/
Traceback (most recent call last):
  File "/remote/sw/beat.env.web-0.0.1/usr/lib/python2.7/site-packages/django/core/handlers/base.py", line 132, in get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/remote/sw/beat.env.web-0.0.1/usr/lib/python2.7/site-packages/django/views/decorators/csrf.py", line 58, in wrapped_view
    return view_func(*args, **kwargs)
  File "/remote/sw/beat.env.web-0.0.1/usr/lib/python2.7/site-packages/django/views/generic/base.py", line 71, in view
    return self.dispatch(request, *args, **kwargs)
  File "/remote/sw/beat.env.web-0.0.1/usr/lib/python2.7/site-packages/rest_framework/views.py", line 466, in dispatch
    response = self.handle_exception(exc)
  File "/remote/sw/beat.env.web-0.0.1/usr/lib/python2.7/site-packages/rest_framework/views.py", line 463, in dispatch
    response = handler(request, *args, **kwargs)
  File "/remote/sw/beat.web/src/beat.web/beat/web/common/api.py", line 62, in post
    self.do_share(object_db, data)
  File "/remote/sw/beat.web/src/beat.web/beat/web/common/api.py", line 50, in do_share
    obj.share(users=users, teams=teams)
  File "/remote/sw/beat.web/src/beat.web/beat/web/common/models.py", line 230, in share
    self._update_sharing(sharing, users, teams)
  File "/remote/sw/beat.web/src/beat.web/beat/web/common/models.py", line 306, in _update_sharing
    shared.send(sender=self, users=users, teams=teams)
  File "/remote/sw/beat.env.web-0.0.1/usr/lib/python2.7/site-packages/django/dispatch/dispatcher.py", line 201, in send
    response = receiver(signal=self, sender=sender, **named)
  File "/remote/sw/beat.web/src/beat.web/beat/web/common/signals/handlers.py", line 63, in on_shared
    action.send(sender.author, verb=verb, target=sender, public=public)
  File "/remote/sw/beat.env.web-0.0.1/usr/lib/python2.7/site-packages/django/dispatch/dispatcher.py", line 201, in send
    response = receiver(signal=self, sender=sender, **named)
  File "/remote/sw/beat.env.web-0.0.1/usr/lib/python2.7/site-packages/actstream/actions.py", line 110, in action_handler
    check(obj)
  File "/remote/sw/beat.env.web-0.0.1/usr/lib/python2.7/site-packages/actstream/registry.py", line 110, in check
    'to register it.' % model_class.__name__)
ImproperlyConfigured: The model Search is not registered. Please use actstream.registry to register it.

This problem also occurred with the Plotter, but I solved it in another patch. Must be done for Search as well