* 8 character long alphanumeric key authentication (server-side)
* Modified integration test to skip the previously mentioned key authentication
* Fixed a previously made typo, which caused the server to await until a single
client's connection was done
* Simplified the structure of client.rs & server.rs a lot, also improved comments
* Confirm client's connection request with SYN
* Version bump, v0.2.0 => v0.3.0
