Search bar: ensure a minimum height

On some themes the natural size of a search entry makes the contact
search bar harder to notice. This uses the natural height of the
search entry in the Adwiata theme as the minimum.

Change-Id: Id9493e3d866c58f0248cc063d10370227b9d6c3b
Tuleap: #353
diff --git a/ui/ringmainwindow.ui b/ui/ringmainwindow.ui
index a78a44f..3f73fcc 100644
--- a/ui/ringmainwindow.ui
+++ b/ui/ringmainwindow.ui
@@ -142,6 +142,8 @@
                     <property name="xalign">0.5</property>
                     <property name="truncate-multiline">True</property>
                     <property name="max-length">256</property>
+                    <!-- ensure a min height (this is the natural height in adwiata)-->
+                    <property name="height-request">34></property>
                   </object>
                   <packing>
                     <property name="expand">True</property>