More Stream Faceting parameters

[mdornseif]

Currently Stream Faceting only allows to select on Photos, which allows besides other things Instagram like applications - which is awesome. But to build other innovative applications more stream faceting options would be very helpful. I myself really would like to see has_geolocation (see also #356 for state of location search).

Faceting by a certain client_id would also be helpful but I expect that this needs bigger server site resources because it would not be boolean.

Having faceting available would be especially helpful since we don't have machine only posts available in the search API.

[rbeeger]

Being able to facet on specific annotation types would also be helpful or at least faceting on some new post field like post_type that could be filled by the client. Faceting on client_id is problematic in my opinion as it would prevent other apps from handling specific types of posts.