Support docker 0.6.5, as the docker introduces two breaking changes.

docker 0.6.5 changes its behaviour
of NAT-routing the container's port and the public port.

Also, docker 0.6.5 changes the output of `docker port` command,
as shown below:

```
45132
```

```
0.0.0.0:45132
```

In order to support docker 0.6.5 output, modify Rakefile.

This commit fixes #263.
Merge branch 'id/263' into dev
Fix Rakefile to work properly.

This commit fixes #263.
Merge branch 'id/263' into dev