Implement unit tests

[ncouture]

We need unit tests.

For starters here are a some unit tests that are also using SSH:

• https://github.com/simon-engledew/sshim/tree/master/tests
• https://github.com/fabric/fabric/blob/master/tests/server.py
• https://sourcegraph.com/github.com/softlayer/swftp/tree/master/swftp%2Ftest%2Ffunctional%2Ftest_sftp.py

[ncouture]

Added an example unit test, it depends on running the example mock_cisco.py manually.

https://github.com/ncouture/MockSSH/tree/master/tests/test_mock_cisco.py

[claudyus]

My PR #8 resolve dependencies over running server manually.

[ncouture]

The threadedServer implemented by claudyus is a good way to perform end to end tests for one MockSSH server however only one twisted reactor can run at a time and reactors cannot be restarted.

Test failure by uncommenting the tearDownClass classmethod in https://github.com/ncouture/MockSSH/blob/master/tests/test_mock_F5.py and running the unit tests.

[ncouture]

• https://twistedmatrix.com/documents/current/core/howto/trial.html