Update app version for Webdav impl of files GUI

This will make sure the cached JS gets properly updated.
Also, since this is a bigger change it also qualifies for a version
increase :-)

apps/files/appinfo/info.xml

@@ -8,7 +8,7 @@
 	<shipped>true</shipped>
 	<standalone/>
 	<default_enable/>
-	<version>1.3.0</version>
+	<version>1.4.0</version>
 	<types>
 		<filesystem/>
 	</types>