Make sure the container is running before testing against it (TestAttachDetach)
Add a GetPtyMaster() method to container to retrieve the pty from an other package.

We could also have put ptyMaster public, but then we need to ignore it in json
otherwise the Marshalling fails. I think it is cleaner that way.
Make the PTY in raw mode before assert test (TestAttachDetach)
Actually test the detach (was not the case before)
Fix term.RestoreTerminal behavior
Make sure the termcaps are restored after hijack
Create helper function for tests
Fix TestAttachDetachTruncatedID (behavior + tty issue)
Remove an unit test from integrations test
Fix behavior of tty tests