Add wait for contexts ready

[mikenikles]

Status: Ready for Review Note: This PR depends on #58 to be merged first.

Changes

• Added a new waitForContextsReady command
• Added test cases for the above

  Todos:

• [x] Passed linting check (run grunt lint)

  How To Test

• Checkout this branch
• npm install
• npm test

[ellenmobify]

👍