refactoring (see details below)

* upgraded xml-dsig and xml-c14n, updated for their major API changes (i.e.
  sync to async)
* added fingerprint functionality in addition to whole-certificate provision
* removed middleware example
* switched from terribly-generated code from xsd to less-terribly-generated
  code from xsd, using jsonix and jsonix-smart
add docco, add package.json script entry
bump version