Set first run dialog window title

Author: elpaso

src/ui/qgsfirstrundialog.ui

@@ -11,7 +11,7 @@
    </rect>
   </property>
   <property name="windowTitle">
-   <string>Dialog</string>
+   <string>Welcome to QGIS</string>
   </property>
   <layout class="QGridLayout" name="gridLayout_2">
    <item row="2" column="1">