Uses Granite.SearchBar which is deprecated

Several elementary apps use Granite.SearchBar which is deprecated in favor of Gtk.SearchEntry as of GTK 3.12

Applications that are already migrated to GTK 3.12 should use Gtk.SearchEntry. However, if the app does not require 3.12 for something else yet, this is probably not a good idea.

Example of migration from Granite.SearchBar to Gtk.SearchEntry can be found at https://code.launchpad.net/~elementary-apps/noise/Gtk.SearchEntry/+merge/225408

List of remaining occurrences of Granite.SearchBar in our applications:

appcenter/src/Widgets/Toolbar.vala: public SearchBar searchbar;
appcenter/src/Widgets/Toolbar.vala: searchbar = new SearchBar(_("Search Apps"));

euclide/src/main.vala: SearchBar search_bar;

granite/demo/GraniteDemo.vala: var search_entry = new Granite.Widgets.SearchBar ("Search");

scratch/src/Widgets/SearchManager.vala: public Granite.Widgets.SearchBar search_entry;
scratch/src/Widgets/SearchManager.vala: public Granite.Widgets.SearchBar replace_entry;
scratch/src/Widgets/SearchManager.vala: search_entry = new Granite.Widgets.SearchBar (_("Find"));
scratch/src/Widgets/SearchManager.vala: replace_entry = new Granite.Widgets.SearchBar (_("Replace With")