Fix test dependency issues using random seeding

[mbklein]

Changes in this PR:

• Add choma for repeatable, randomized test ordering
• Make mocked event updaters idempotent
• Ensure all environment updates happen in a beforeEach() or an it() block
• Ensure all describe() blocks containing environment updates start with helpers.saveEnvironment()
• Fix corrupted blocks in api-token.test.js that had a bunch of test code running outside of it() blocks
• Use a stack for saving/restoring the environment instead of a single variable (to support nested describes)

[bmquinn]

Looks great 👍