add dependency on unittest for development

[tomato42]

No description provided.

[tomato42]

@FiachAntaw: could you take a look? Should fix the issue with CONTRIBUTING.md you mentioned in #80

[FiachAntaw]

I think the 'mock' module is distributed as a separate module for python 2 and isn't included in unittest2. It's needed by unit_tests/test_tlslite_recordlayer.py.

I'm testing the dependency list by doing the following to generate a fresh virtualenv:

cd tlslite-ng
# Make python2 virtualenv (needs virtualenv/virtualenvwrapper)
mkvirtualenv tlslite-test -p `which python2`
# Add local python3 binaries/libraries to the virtualenv
mkvirtualenv tlslite-test -p `which python3`
# Install dependencies
pip install unittest2 ecdsa pylint diff_cover coverage hypothesis tackpy m2crypto pycrypto gmpy
pip3 install ecdsa pylint diff_cover coverage hypothesis tackpy m2crypto pycrypto gmpy
# Run tests
make test-dev

Which at present fails with an ImportError on mock in the aforementioned file. Running pip install mock fixes the problem and all tests then complete without errors.

[tomato42]

@FiachAntaw how about now? I've added explicit dependency on mock

[FiachAntaw]

Looks good to me.