Can't connect to a local HipChat server

[davestephens]

Although HipChat is on its way out, there are still a few of us using it in corporate settings until we can get it removed and replaced with Slack.

With that in mind, the current version of the image won't connect to our HipChat server, see errbotio/errbot#1144 for details of others with the same issue.

Specifying specific pip packages in requirements.yml fixes the issue:

sleekxmpp==1.3.2
pyasn1==0.3.7
pyasn1-modules==0.1.5