Test file cleanups
Statement class changes for spec 1.0

* Deprecate 'voided' property per spec 1.0
* Add 'version' property per spec 1.0
* Switch asVersion to protect against required properties not having
  values, presumably calling system could add them directly or something
  no reason to fail, should just be silent on it
* Switch constructor second property to be an object with backwards
  compatibility with existing flag, add 'doStamp' option to that
  configuration, allows for additional configuration of the
  initialization process
* Add stamp() method
* Adds significant unit test coverage of Statement model