fix raspberry pi arch ZMQError: Address family not supported by protocol
Merge pull request #596 from y12studio/raspberry-pi-arch-fix

fix raspberry pi arch ZMQError: Address family not supported by protocol
Move and refactor transport tests.

* Move transport tests to test folder.
* Refactor tests in unittest format; use mocks.
* Improve code style.
Drop run_tests.sh.

* Unit tests should be run by calling `nosetests` on the project home
  directory.
Improve contact tests.

* Factor guid and uri in setUpClass.
* Test __repr__ is implemented and __str__ derived.
Merge pull request #594 from Renelvon/more_tests

Unit test node/transport.py and expand tests of node/contact.py.
Initial cleanup of node/crypto_util.py

* Drop unused code.
* Fix import style.
* Abstract the Elliptic Curve used.
* Suggest to replace any occurences of 'secp256k1' in rest of codebase
  with crypto_util.BTC_CURVE
Initial commit of tests.