Refactor Is_manager logic

[lumjjb]

MOVED FROM ORIGINAL REPO https://github.com/lumjjb/tornjak/issues/25

Currently IsManager logic is intertwined into the main logic of most components, however, each of the individual components don't necessarily need to know if it is in manager mode or not if the dataset presented to it is filtered.

This is issue is around moving the use of IsManager to a abstraction where most of the UI components don't need to know whether it is running as a manager. For example, agent list doesn't need to know if its a manager, it just needs to be given the right dataset.