Rework the StreamingLearnerInvestigator

[BenCarter44]

From part 2 from #25.

Rework the StreamingModelInvestigator:

• Remove the StreamingActiveLearner dependency. Have the user provide the ROSE AL learner they wish to use in the constructor (or require user to subclass to provide the learner).
• The investigator does its own simple batching.
• Automatically publishes models generated by the learner.

This would also require adjusting the tests to match.

[BenCarter44]

Wrote up a draft spec of the new StreamingLearnerInvestigator. See #29