chore: remove mentions of pycrypto (#799)

Author: busunkim96

README.md

@@ -58,7 +58,6 @@ The following libraries will be installed when you install the client library:
 
 For development you will also need the following libraries:
 * [WebTest](http://webtest.pythonpaste.org/en/latest/index.html)
-* [pycrypto](https://pypi.python.org/pypi/pycrypto)
 * [pyopenssl](https://pypi.python.org/pypi/pyOpenSSL)
 
 ## Contributing

tox.ini

@@ -11,7 +11,6 @@ deps =
        google-auth-httplib2
        mox
        pyopenssl
-       pycrypto==2.6
        django<2.0.0; python_version < '3.0.0'
        django>=2.0.0; python_version > '3.0.0'
        flake8