Implement proper XML output

[binfalse]

The XML output of BiVeS currently looks a bit shitty...

<?xml version="1.0" encoding="UTF-8"?>
<bivesResult>
  <documentType>["XML","SBML"]</documentType>
  <meta>{"nodestats":{"listOfCompartments":1,"reaction":1,"species":2,"compartment":1,"listOfSpecies":1,"listOfProducts":1,"listOfReactions":1,"model":1,"sbml":1,"speciesReference":2,"listOfReactants":1},"modelName":"test_model","sbmlVersion":3,"sbmlLevel":2,"modelId":null}</meta>
</bivesResult>

Do proper name spaces and convert the JSON to proper XML... (maybe in https://github.com/SemsProject/XMLUtils?)