Serve configs like xml curl

From FreeSWITCH Wiki

io.write("TEST\n" .. params:serialize("xml") .. "\n");

XML_STRING = [[

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<document type="freeswitch/xml">
  <section name="dialplan" description="RE Dial Plan For FreeSwitch">
    <context name="default">
      <extension name="test9">
        <condition>
         <action application="lua" data="/tmp/test.lua"/>
        </condition>
      </extension>
    </context>
  </section>
</document>

   ]]