Fix rllab dockerfile before migration to garage

[j3soon]

This PR resolves issues about running the provided code in Docker with rllab.

The migration from rllab to garage appears to overlook Docker usages, thus it may be harder to fix.

I have fixed some of the docker issues regarding the migration to garage in another branch (the fix-garage branch). If I somehow managed to fix all issues, I'll open another PR for it.

I'll leave this as a draft for now, making it a potential reference for other docker users.