Add Jest support

[dmitry-zaets]

• Add Custom Matchers for Jest:
  • toDispatchActions
  • not.toDispatchActions and/or toNotDispatchActions
  • withState
• Add Tests for Jest
• Add Tests with Jest as a step to npm test
• Add Jest to Readme
• Add Jest docs page with usage examples

[adamyonk]

I don't have time to do this right now, so leaving this here as a quick tip for anyone who needs it working ASAP:

  it('should run the correct actions', () => {
    return assertions.toDispatchActionsWithState(
      state,
      action(arg),
      expected,
      // done will be a thrown error if actions don't match expected
      done => expect(done).toBeUndefined()
    )
  })