Add iproute2 package to Docker image

[Gulluth]

I have successfully installed theonionbox using a modified version of your Dockerfile. When using it as-is, theonionbox app exits with an error.

"FileNotFoundError: [Errno 2] No such file or directory: 'ip': 'ip'"

The fix for this is to install the package 'iproute2'

I have added the following line to the Dockerfile.

RUN apt update && apt install -y iproute2

[Linutux]

Could you provide the docker file you used?