Add option to disable pseudo-tty on fig run

Also disable tty if stdin is not a tty.
Use raw socket in 'fig run', simplify _attach_to_container
Update docker-py

Brought in changes from https://github.com/dotcloud/docker-py/pull/145
Merge pull request #34 from orchardup/better-tty-handling-for-fig-run

Add option to disable pseudo-tty on fig run