Stop & Kill options for containers removal

Closes #6533

**docker rm**:
`-f/--force`: deprecation warning.
`-s/--stop`: stop then remove a container.
`-k/--kill`: kill then remove a container

**API**:
`DELETE /containers/(id)`
`DELETE /containers/(name)`

`force`: stop then remove a container.
`kill`: kill then remove a container.
Sorry I read a bit too quickly.

`container.Stop` should really takes a `time.Duration` but that can addresssed in a separate PR.