Proposal: define schema for the core app scopes: network & health

[mikkelhegn]

We should define the schema for the two core application scopes: Network and Health, so that it's not left to the individual implementation to define what can and cannot be done.

Currently these are just examples: https://github.com/microsoft/hydra-spec/blob/master/4.application_scopes.md#network-scope and https://github.com/microsoft/hydra-spec/blob/master/4.application_scopes.md#health-scope

In the case an implementation will go beyond the core scope definition, extended application scopes can be defined by that implementation.

[hongchaodeng]

I will take on the work.
@wonderflow is working on Health Scope implementation. We will work together.