Investigate How to Calculate Priority by Datacenters and Nodes

[VictorCavichioli]

Story Description:
In the current implementation ecchronos calculate priority by nodes, to understand how it works it is described in the architecture documentation, the idea is to create a similar structure to reuse the current priority and determine the datacenter priority; the process would be:

1. Determine the priority of each node;
2. Create Nodes Queue (Optional for the definition of priority);
3. Calculate the absolute DC priority (SUM of each node priority/number of nodes in the datacenter).

Acceptance Criteria:

• Code designed as described;
• Unit and integration tests done;
• Documentation updated.

Definition of Done:

Code designed as proposed, test cases passing and approved by maintainers.

Notes:

Related to #677 and #652