Places is one of the dash sections and it should be included in search results.
Factor out the code for getting and updating the information about places from
Places to PlacesManager.
Introduce PlaceInfo class that contains information about the place and can be
used by classes that display it in different ways. Rename classes so that their
names are consistent with corresponding classes in appDisplay.js and
docDisplay.js
https://bugzilla.gnome.org/show_bug.cgi?id=599125
