appDisplay: Animate AllView and FrequentView

Following design decision, we want to animate AllView and FrequentView
when opening and closing with a swarm spring form.

This involves a few changes needed to allow that, since from some time
now, we are animating page changes in viewSelector, using only a fade
transition. However now we want to let appDisplay and iconGrid apply its
own animation.

For that we special case the change to and from apps page on
viewSelector to let appDisplay to animate its own items, using and API
on appDisplay which at the same time uses an API on iconGrid.

However animating the icons in iconGrid involves a few challenges due to
the current need of scaling icons on iconGrid on a call which uses
BEFORE_REDRAW.  We need to call animate() after the icons are already
scaled, that means however, calling after a BEFORE_REDRAW, so that
means, we have to call animate() in a call using BEFORE_REDRAW which
call a function using BEFORE_REDRAW as well, so we wait two frames to
make sure icons are scaled correctly.

Thanks Florian Mullner for the debugging work

https://bugzilla.gnome.org/show_bug.cgi?id=734726
appDisplay: Animate indicators out

Given that we animate indicator in, it makes sense to animate them out
as well.

https://bugzilla.gnome.org/show_bug.cgi?id=734726
Search: cleanup unused code

https://bugzilla.gnome.org/show_bug.cgi?id=734726
Search: Use AppIcon for gridResults

Currently GridResult and ListResult inherit from a base class named
SearchResult which creates a StButton as a base item.
Then GridResult put as a child of the StButton an AppIcon created on
provider.createResultObject. But, StButton lacks some features of
AppIcon like dnd, style, etc. So GridResult add those in the class and
also adds the style of the AppIcon on the theme.

Obviously that doesn't look very appealing, so instead of that, delete
the base class and provide AppIcon some API needed by
Search and then use directly AppIcon on GridResult.

https://bugzilla.gnome.org/show_bug.cgi?id=734726
Search: Animate new window of apps in AllView and FrequentView

Following design mockups, animate the icons on AllView and FrequentView
to zoom out when opening a new window of the app or when the app is not
running and the user execute it.

https://bugzilla.gnome.org/show_bug.cgi?id=734726
iconGrid: Move code around a bit

The scale passed to _updateChildrenScale is exclusively computed from
properties, so it can be moved into the function itself - as the scale
now becomes a mere detail, rename to a more appropriate _updateIconSizes
at the same time.