Code Generator improvements for Python and NodeJS API v3

Some parts of the Code Generator failed, and so the generated code examples were broken. Following parts were fixed

• Substituted Types need an xsi:type definition. These type was added for Python and NodeJS. Applies to API v3: request, mark
• Python:
  mark_type = client.get_type('v3:TreatyOrStatuteMark')
mark = mark_typ
  Show Python example API v3
• NodeJS:
  attributes: { xsi_type: { type: "http://www.ascio.com/2013/02", xmlns: "TreatyOrStatuteMark" } }
  Show NodeJS example API v3