Sequential subjects

[saschaishikawa]

Summary of Changes

• Implements a subject set utility that provides a basic CLI to manage OW ships. Features include 1) listing subject sets available to current active user, 2) ability to activate/deactivate subject sets, 3) generate a linked list within a subject set provided pageNumber is defined for each subject
• Ensures default workflow, project.configuration.default_workflow is used in place of the ambiguous project.links.workflows[0]

Linked List Implementation Details

The subjectFactory keeps track of the current_subject. If current_subject.metadata.nextSubjectId exists, then the next subject is fetched by that ID; otherwise, a random unseen subject is fetched. As is, subjects are only "cached" one-at-a-time. To do: Experiment with creating linked list with arrays of prev and next IDs to cache in batches greater than 1.

[saschaishikawa]

@itsravenous: I think this PR is finally ready to review. Lemme know if you run into any problems.