setup.py "extras" doesn't line up with documentation

[hosford42]

The installation instructions at the top of README.md suggest this installation command:

pip install "pycozo[embedded,requests,pandas]"

But when I run it on the command line, I get this warning:

C:\...\pycozo> pip install "pycozo[requests]"
WARNING: pycozo 0.7.6 does not provide the extra 'requests'

This is because setup.py names the extra client instead of requests:

    extras_require={
        'pandas': ['pandas', 'ipython'],
        'embedded': ['cozo-embedded==' + VERSION],
        'client': ['requests']
    },

I can easily put together a pull request for this, but I'm unsure whether you'd prefer to rename the extra or adjust the documentation.