Always using pycrypto for key generation

[awwad]

In the current keys.py, line 1702, regardless of which library you are configured to use (pycrypto or pyca_crypto), pycrypto is used to generate key files. This appears to be a typo / minor oversight, since there is logic to choose one or the other.

This is related to issue #44, in that it also complicates inconsistent passphrase treatment.

In any case, this prevents you from generating keys if you don't have pycrypto installed. (That should be supported: you're allowed to use pyca_crypto and not pycrypto if you want.)

It is also worth considering configuring tox.ini to do an integration test for this: run once with only pycrypto (not pyca_crypto) installed, once with only pyca_crypto (not pycrypto) installed, etc.

[vladimir-v-diaz]

Fixed in e8aafd8.