Fix problem when merging manifests

AndroidManifest.xml

@@ -1,5 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
     package="eu.siacs.conversations"
     android:versionCode="31"
     android:versionName="0.7.3" >
@@ -22,6 +23,7 @@
         android:allowBackup="true"
         android:icon="@drawable/ic_launcher"
         android:label="@string/app_name"
+        tools:replace="android:label"
         android:theme="@style/ConversationsTheme" >
         <service android:name="eu.siacs.conversations.services.XmppConnectionService" />