servefile used to hint to install pyssl when ssl support was missing.
This is utterly wrong, because the package is named pyopenssl - as
stated in setup.py. Installing pyssl will not only not lead to ssl
support, but also install a random package that we do not want.
Also, since python2 has genereally been deprecated (though it is still
support by servefile for now) we hint for the python3 package of
pyopenssl instead of the python2 version. I thought about building a
version detection and print the right package, depending if the user is
using python2 or 3, but I deemed it not being worth it.
Fixes#7 (GitHub)