Python depends for telnet tls

[robotfactory]

Brief overview of PR changes/additions

Allows for tls on telent out of the box when starting up a docker container

Addresses feature request in issue #1637

Installs py2-openssl as well as cryptography, pyasn1, and service_identity

Motivation for adding to Evennia

Allows for tls on telent out of the box when starting up a docker container

Other info (issues closed, discussion etc)

[inquisitivecrystal]

I'm just a random passerby, but... What's the motivation for adding the PIP dependencies to the Dockerfile, rather than requirements.txt? Are they only applicable to Docker containers?

[robotfactory]

On my first look it appeared to only be an issue when launching in Docker. The more I thought about it, the more it made sense to put it in requirements.txt. I don't know if maintainers had a reason for NOT listing in requirements.txt, though. So that's worth discussion.

[Griatch]

The reason for not having the pycrypto dependency in the requirement file is because not everyone wants or care about Telnet encryption (it's not active by default) so this is an optional install. Also, using the crypto required/requires some additional setup that was not something we wanted to incur on new users.

The dockerfile is a different thing in that respect - there it becomes a hindrance to not have the packages available.

We'll need to rework the dockerfiles for the develop branch of Evennia anyway, so this has not been a priority. But it sounds reasonable to me to merge this for master for now.