Added converters.xml file

Each new converter definition requires an entry in the converters.xml file. This file is readed from converter.Form.js file to load dinamically the converters avalaible
Method GET with the parameter "converters" returns converters.xml file

If not necessary pass some value into converters parameter
Modified converters.xml

Modified converters.xml file to simplify its use with the Model
Create converter institution buttons dinamically

Reads XML file across an Ajax petition an load buttons with the Institution name
Load buttons Converter $ fixes string in globalmetadata.xml