Implement configurable detach keys (for `attach`, exec`, `run` and
`start`) using the client-side configuration
- Adds a `--detach-keys` flag to `attach`, `exec`, `run` and `start`
commands.
- Adds a new configuration field (in `~/.docker/config.json`) to
configure the default escape keys for docker client.
Signed-off-by: Vincent Demeester <vincent@sbr.pm>
Vincent Demeester