ui: adding backgrounds

- adds backgrounds to wizard dialog, welcome page, outbound/invite
pages.

Change-Id: Id76ee5f67f80513d39c51327f4d42bf4129edb8f
Tuleap: #148
diff --git a/ressources.qrc b/ressources.qrc
index f652782..77f7b25 100644
--- a/ressources.qrc
+++ b/ressources.qrc
@@ -30,5 +30,7 @@
         <file>images/icons/ic_settings_white_48dp_2x.png</file>
         <file>images/icons/ic_voicemail_white_24dp_2x.png</file>
         <file>images/icons/ic_share_white_24dp_2x.png</file>
+        <file>images/background-light.png</file>
+        <file>images/background-dark.png</file>
     </qresource>
 </RCC>