Prepare HyperBEAM application for release

[oltarasenko]

We don't have a release configuration (https://rebar3.org/docs/deployment/releases/) that would allow us to ship the application as self-contained tar files configurable on the target nodes. Our task is to:

1. create a release configuration
2. allow the HyperBEAM post configuration (so we don't have to re-compile anything if we want to change for example storage backend)
3. describe the release process in the doc