Jest tests

[thejefflarson]

This is a pull request for tests for the frontend, and also represents a cleanup of sorts. We have a the beginnings of a test rig, and full tests for actions.js. Todos:

• [x] build test rig
• [x] test actions
• [x] merge in master and put things in the right place
• [x] test reducers
• [x] test components

@jeremybmerrill I'll handle the merge, but can you review what's going on so far?

[jeremybmerrill]

Looks good to me so far. I'm working on the merge. Big fan of separating out actions, etc. into their own file.

[jeremybmerrill]

I've finished tests for the Admin components.

[thejefflarson]

\o/