more tests for cheque
add voucher tests
fix voucher tests
add tests for acount to acount transfer
skip problematic tests
small cleanup
Refactor into classes, fix and clean up tests

   Now have higher level abstraction classes like Nym, that
   still allow us to test the server with bad data.

   Also added error.py which easily lets us test for expected error
   conditions.

   Added multimethods to requirements.txt to support generic transfers,
   and also support error lib
Merge pull request #10 from 0x01--/pr/7

Refactor into classes, fix and clean up tests