Replace deprecated lifecycle methods

[DoctorHowser]

componentWillRecieveProps and componentWillMount are deprecated and throwing warnings in the console. Refactored the code to use the new getDerivedStateFromProps method.

Refactored accordingly, as getDerivedStateFromProps needs to return the new state.

[coveralls]

Coverage decreased (-1.4%) to 81.517% when pulling e21658e on DoctorHowser:master into 6f7ec60 on headzoo:master.

[headzoo]

Looks good. I'm trying to track down the cause of this warning in the tests:

console.error node_modules/react-dom/cjs/react-dom.development.js:506
  Warning: PropChangeContainer: It is not recommended to assign props directly to state because updates to props won't be reflected in state. In most cases, it is better to use props directly.

I'll merge and push once I find the problem.