Use ' instead of " for quoting strings in SPARQL

Consistency makes it easier to copy paste strings from the debug
output into tracker-sparql(1), and ' does not need to be escaped in C
string literals.
item-manager: Do not crash when a photo is deleted underneath

Removing an item from PhotosItemManager will destruct it, unless it is
a collection. Do it at the end to avoid having an invalid pointer for
the rest of the block.

Fixes: https://bugzilla.gnome.org/725813
Selection and search should be disabled when there are no photos

Since the visibility of toolbar buttons now depend on the current
PhotosViewModel, we need to reset the toolbar and set the model in a
well defined order. Therefore we reset the toolbar from PhotosEmbed
before setting the model, instead of having it separately listen to
ModeController::window-mode-changed.

https://bugzilla.gnome.org/show_bug.cgi?id=725587
view-model: Reset the count when items are removed

Fixes: https://bugzilla.gnome.org/726162
overview-searchbar: Refocus the search entry after changing filters

Original patch from Rohit Agarwal for gnome-documents.

Fixes: https://bugzilla.gnome.org/726165
view-container: Prevent the icons from shifting around

The album and photo icons are not exactly of the same size because we
do not frame the albums. This causes the icons to shift horizontally
when moving from a view with only albums to one that has both albums
and photos. So lets set an item width on the GtkIconView to avoid this.

Fixes: https://bugzilla.gnome.org/698941
main-toolbar: Add searchbar in selection mode

https://bugzilla.gnome.org/show_bug.cgi?id=725934