Feat: Functional tests.

[jaoleal]

As saw #198 (comment). were only certain that our implementation is properly working if we run the node. This is not ideal because is resource and time consuming, not all devices that can be used to develop rust code can easily run the node.

This issue is to keep track of implementing new functional tests. Such as:

Specific blocks evaluation.
Mass blocks evaluation.
Conection with other nodes.

A good example to follow is the functional tests on Bitcoin Core.