Report number of times that docker has auto-restarted a container

Fixes #9469.

The docker inspect command now displays the number of times that a container was restarted.

To test it, run the following commands:
```
# ./docker-1.3.3-dev run --name nginx --restart always -d nginx
14f7f3a2f2a32bdb8356ac015d60a1d38f0d0785537ed6ee8cf6d7f47f7211f0
# ./docker-1.3.3-dev inspect -f "{{.RestartCount}}" nginx
0
# kill -9 $(./docker-1.3.3-dev inspect -f "{{.State.Pid}}" nginx)
# ./docker-1.3.3-dev inspect -f "{{.RestartCount}}" nginx
1
```

Signed-off-by: Rémy Greinhofer <remy.greinhofer@livelovely.com>
Why not `SetInt`?