Fix warnings in unit tests

[nranas]

We're getting these currently:

PASS  __tests__/am-pm-tests..js
  ● Console
    console.error node_modules/fbjs/lib/warning.js:36
      Warning: Shallow renderer has been moved to react-test-renderer/shallow. Update references to remove this warning.

The tests are still passing but we should get rid of the warnings since they will eventually turn in to errors.

[nranas]

I have fixed most of the warnings in #122. The few that are still left comes from react-widgets which have fixed them in version 4 (currently on rc6). When v4 is stable we should upgrade to that and the warnings should disappear.