Ubuntu 16.04: libssl-dev required

[uolot]

Hi,

I think it'd worth being mentioned in "dependencies" section, that libssl-dev is required (for Ansible). Without having it, installation fails when installing Python's requirements with:

  Failed building wheel for cryptography
Command "/home/twalotek/Dev/i3-xfce/venv/bin/python2 -u -c "import setuptools, tokenize;__file__='/tmp/pip-build-ygtJZK/cryptography/setup.py';f=getattr(tokenize, 'open', open)(__file__);code=f.read().replace('\r\n', '\n');f.close();exec(compile(code, __file__, 'exec'))" install --record /tmp/pip-xjEya4-record/install-record.txt --single-version-externally-managed --compile --install-headers /home/twalotek/Dev/i3-xfce/venv/include/site/python2.7/cryptography" failed with error code 1 in /tmp/pip-build-ygtJZK/cryptography/

Best regards,
Tomasz