Add pycrypto to requirements.txt

[SamJoan]

Hi there,

In my case, when following the instructions on the cowrie installation page, I got this error:

(cowrie-env)cowrie@hostname:~/cowrie$ ./start.sh cowrie-env
Activating virtualenv "cowrie-env"
Starting cowrie with extra arguments [] ...
An error has occurred: b'ImportError: No module named Crypto.PublicKey'
Please look at log file for more information.

I am not sure why this happens, and nobody else has opened an issue for this bug, but the solution is simple so I thought I'd make a PR.

Cheers,
Pedro

[ryd994]

Do you want to remove crypto ?
As it is actually an gpg encrypt package.
Check https://pypi.python.org/pypi/crypto

[SamJoan]

That seems like it'd make sense, I've removed it from my branch.

[micheloosterhof]

Thanks!