fix encryption errors

[ajuniper]

These fixes address the issues seen in issue #294
I'm not a Python expert so they might be solid in all environments but they work for me...

[charliejllewellyn]

Nice thanks for this fix, it worked for me :) There is an error on line 170 though where you have an extra "("

return encryptor.update((bytes(payload)) + encryptor.finalize() should be
return encryptor.update(bytes(payload)) + encryptor.finalize()

Hopefully someone merges this soon :)

[felipediel]

HI @ajuniper. It seems that this problem still exists. Could you please resolve the conflicts so we can merge?

[felipediel]

I resolved conflicts and merged. Thank you very much @ajuniper!

[ajuniper]

@felipediel Apologies for not commenting sooner, been AFK. Glad you resolved the conflicts.