Revise learning objectives using Bloom's Taxonomy

[qjcg]

Following the discussion in PR #63, we will pilot rewriting our lesson objectives with reference to Bloom's Taxonomy.

To start, we will aim to follow the two-level grouping of objectives suggested by @ErinBecker.

PRs with revised objectives should be made against the new-learning-objectives branch of this repo.

[tracykteal]

@kariljordan @ErinBecker I think this is done for these lessons now?