The following changes make message tray look more polished:
- all notifications are now same width (no min and max width)
- there is an equal padding all around the notification (which resulted in
the increased tray height)
- action buttons are now nicely styled
- chat text box glows when focused (nevermind the unfocused look because
we'll soon always have it focused when it is showing)
- chat text has padding on the left and rounded background
- summary source buttons no longer have a border
https://bugzilla.gnome.org/show_bug.cgi?id=624584
6eb90434f0
