Add handler back to install button

plugin_installer/config_dialog.ui

@@ -269,6 +269,7 @@
                         <property name="sensitive">False</property>
                         <property name="can_focus">True</property>
                         <property name="receives_default">True</property>
+                        <signal name="clicked" handler="on_inslall_upgrade_clicked" swapped="no"/>
                         <child>
                           <object class="GtkHBox" id="hbox6">
                             <property name="visible">True</property>