Filter containers by status.

A continuation of #7616.
Closes #7616.
Adds `docker ps --filter=status=(restarting|running|paused|exited)` option.

Docker-DCO-1.1-Signed-off-by: Jessica Frazelle <jess@docker.com> (github: jfrazelle)
shouldn't this be `==1`? I believe this test working if your filter filters nothing at all. For example you wanna id `blabla` with exited status. You get:
```
blabla
foofoo
```
from docker `ps -a -q filter`(which is wrong), but your test will pass as I see.
Probably better not try to bring `DRY` in tests. Maybe you just should run 5-6 containers with different status and the one by one test filters.