Can't get libev to work with pypy

[Richard-Mathie]

$> docker run --rm -it ricmathie/python_cassandra
>>> from cassandra.io.libevreactor import LibevConnection
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python2.7/site-packages/cassandra/io/libevreactor.py", line 33, in <module>
    "The C extension needed to use libev was not found.  This "
ImportError: The C extension needed to use libev was not found.  This probably means that you didn't have the required build dependencies when installing the driver.  See http://datastax.github.io/python-driver/installation.html#c-extensions for instructions on installing build dependencies and building the C extension.

which results in issues like
from Richard-Mathie/cassandra_benchmark

2017-02-14 15:40:56,348 [WARNING] root: Not benchmarking libev reactor because libev is not available

Dont know if this really matters though...