Improve error output for `docker stats ...`
While looking into `docker stats <c1> <c2> ...` I noticed that
the error output is quite long, especially if there are multiple errors:
```sh
ubuntu@ubuntu:~/docker$ docker stats nofound
: Error response from daemon: No such container: nofound
ubuntu@ubuntu:~/docker$ docker stats nofound foo bar
: Error response from daemon: No such container: nofound, : Error response from daemon: No such container: foo, : Error response from daemon: No such container: bar
```
There are several issues,
1. There is an extra `: ` at the beginning. That is because if container is not found,
the name will not be available from the daemon.
2. Multiple errors are concatenated with `, ` which will be quite long.
This fix:
1. Only prient out the error from daemon.
2. Multiple errors are printed out line by line.
Below is the new output:
```sh
ubuntu@ubuntu:~/docker$ docker stats nofound
Error response from daemon: No such container: nofound
ubuntu@ubuntu:~/docker$ docker stats nofound foo bar
Error response from daemon: No such container: nofound
Error response from daemon: No such container: foo
Error response from daemon: No such container: bar
```
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>