3.0.x switch from docker host using https|http scheme to tcp breaks proxy configure

With the 3.0.x release, the code has been changed to use docker hosts of the format:

```
  tcp://host:port
```

Instead of:

```
  https://host:port
```

This breaks some of the logic in JerseyDockerCmdExecFactory that configures the proxy setting.

I've tested a fix and will create a PR shortly.
