chat: add option for chat to be the right (default)

The chat can now be bellow the video or to the right.
An option for this is added to the gsettings schema and
to the UI. The default is for it to be to the right
like the other Ring clients.

Change-Id: I6db382ac77ce0ed192bb717ee7825471ae8f34ee
Tuleap: #110
diff --git a/data/cx.ring.RingGnome.gschema.xml b/data/cx.ring.RingGnome.gschema.xml
index 80852aa..0f36a23 100644
--- a/data/cx.ring.RingGnome.gschema.xml
+++ b/data/cx.ring.RingGnome.gschema.xml
@@ -21,5 +21,10 @@
         <summary>Saves whether or not the main window is currently hidden or not.</summary>
         <description>This is used when launching the application with the '--restore-last-window-state' option, which will launch the application with the main window in the same state as when it was last quit.</description>
     </key>
+    <key name="chat-pane-horizontal" type="b">
+        <default>true</default>
+        <summary>Display the chat to the rigth (default) or at the bottom.</summary>
+        <description>If the chat pane is horizontal then the chat is displayed to the right of the video; otherwise it will be displayed bellow it.</description>
+    </key>
   </schema>
 </schemalist>