search-type: Use better defaults for "filter" and "where"

Fixes: https://bugzilla.gnome.org/709367
search-type-manager: Clean up

+ There is no need for a builtin "all" PhotosSearchType. We will always
  have the distinction between albums, photos and favorites.
+ Not all albums are nie:DataObjects. Only nfo:DataContainer is
  mandatory.

Fixes: https://bugzilla.gnome.org/709367
view-model: Skip collections in the overview

Fixes: https://bugzilla.gnome.org/709367