BasicUI: escape character data in XML output, fixes #1366 (#1373)

PR: https://github.com/eclipse/smarthome/pull/1373

Signed-off-by: Vlad Ivanov <vlad-mbx@ya.ru>

extensions/ui/org.eclipse.smarthome.ui.basic/snippets/layer.html

@@ -1,5 +1,5 @@
 <page>
-	<title>%label%</title>
+	<title><![CDATA[ %label% ]]></title>
 	<data>
 		<![CDATA[