ephy-toolbar: Use GtkBox instead GtkToolbar

The padding is according the comments of the team design.

https://bugzilla.gnome.org/show_bug.cgi?id=706050
ephy-window: Use the top bar GtkBox as titlebar

The GtkEventBox is to ensure opacity (see
bug #706045).

https://bugzilla.gnome.org/show_bug.cgi?id=706050
ephy-window: Fix the margins in the top bar

https://bugzilla.gnome.org/show_bug.cgi?id=706050
ephy-window: Always show the top bar in app mode and show/hide title according mode window

* In normal mode: show address bar and
  hide title and reload/stop buttons.

* In web application mode: hidde the address bar
  and show instead the page title and the reload/stop button.

https://bugzilla.gnome.org/show_bug.cgi?id=706050
ephy-toolbar: Add close button

https://bugzilla.gnome.org/show_bug.cgi?id=706050