[gnome-contacts] Contacts.Window: fix the look of add button

[Erick Pérez Castellanos <erickpc src gnome org>]

commit 12f65e6b7f72c3d9b188e580dc336c564f53fd2a
Author: Yosef Or Boczko <yoseforb gmail com>
Date:   Sat Aug 17 22:05:08 2013 +0300

    Contacts.Window: fix the look of add button
    
    https://bugzilla.gnome.org/show_bug.cgi?id=706092

 src/contacts-window.ui |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/src/contacts-window.ui b/src/contacts-window.ui
index ed13cc4..1e5b34c 100644
--- a/src/contacts-window.ui
+++ b/src/contacts-window.ui
@@ -22,6 +22,8 @@
               <object class="GtkButton" id="add_button">
                 <property name="visible">True</property>
                 <property name="can_focus">True</property>
+                <property name="halign">center</property>
+                <property name="valign">center</property>
                 <style>
                   <class name="image-button"/>
                 </style>