This fix resolves an issue on EL6 systems where there may be multiple versions
of pycrypto installed.  EPEL provides both `python-crypto` and
`python-crypto2.6`.  These packages are co-installable.  However, modules
importing the `Crypto` library must specify which version to use, otherwise the
default will be used.

This change follows the same pattern established in `bin/ansible` for
specifying python library requirements.