regenerate code with current zproto version.

- clojure server code is now generated via zproto.
- adapt dummy server implementation for test according to new
  requirements by generated server code.
- tests for failed commands currently fail. remove until it is
  clear how failing behaviour should be incorporated in the zproto
  model.
Merge pull request #36 from mknoszlig/master

Problem: clojure server code is outdated wrt current zproto version.