Rust configuration

[nbuffon]

New features

• New client module
• Information struct is now a Message enumeration variant
• Information no longer manages the region of responsibility
• Configuration has been split into Configuration and NodeConfiguration
• NodeConfiguration is an optional part of Configuration which holds server instance information
• Fixed warnings in documentation (closes #106)

Note: exchange.rs contains commented code that will be either deleted or updated in further commits/PR

How to test

Nothing much to do other than checking that build, tests and benches runs correctly In addition from previous PR also build the documentation to check it correctly does with no warnings

1. cargo clean
2. cargo build
3. cargo test
4. cargo bench
5. cargo doc --no-deps --open

[nbuffon]

@Hugues360 I made some changes since you first reviewed this PR, a quick review of the diff could be a good idea