Networking of covid-ht instances

[math-a3k]

A covid-ht instance should be able to connect with other instances to form a network.

This would allow instances to share data and/or applied knowledge via classification services.

If the Node chooses to share data, that data can go after it is input or after it is validated.

Each Node should have a Data Unit with a User for data input and eventually identify the classification requests from the Node.

As the Data may vary from each Node - both in fields and population, the Nodes should allow the classification of other's Node's Data in order to measure performance of the Node classifier with the other Node's Data, and, in the case where data sharing is possible, they should be able to incorporate the unit as a categorical field so the classifier can "discern" between populations if needed.

A mechanism of voting should define the classification of data by each Node if they request classifying services to others.

[math-a3k]

Implemented in 6e11a65, f342459, 279aad6, 7931491, 05f0e90, 676239d, 4cca76c, 19d0547, 1dfca8a, 3fea88b

This issue is related to #6 and #5