[1.x] Make IP to bind the server to configurable via env

[xorinzor]

Building further on #605 this also makes the IP that the server listens on configurable using environment variables when no commandline argument for --host is provided.

The implementation should not break any existing deployments.

[xorinzor]

Ideally all of these arguments should be configurable via the octane config file. However I discovered quite quickly that this would break backwards compatibility with existing deployments unless they updated their config files.

Perhaps this is a breaking change worth considering for 2.0 and add it to a migration guide.
This PR maintains backwards compatibility.