introduce a --remove-broken-containers

When one of your container has a wrong `config`, or `hostconfig` format,
you'll see an error when the docker daemon starts like `[error] runtime.go:321 Failed to load container 86fca1ecde43b7ab3a2d99f82025c998b8c6f420b4d1ff10d348279d6ce45b9b: json: cannot unmarshal string into Go value of type bool` 
The container won't appear anywhere, so there is no way to delete it. Even if you go to the fs and remove the directory, it can leave some name or links behind.

I propose to add a `--remove-broken-containers` to automatically cleanly remove the broken containers.

I wait to see if this feature is worth something before doing docs