Allow PropChangeHock to getIn class instance properties in its prop keys

• PropChangeHock
  • PropChangeHock paths can now contain class instances
  • BREAKING CHANGE PropChangeHock checks each data at each path in paths. Commonly the data at these paths are just primitives, but they can be deep data types too. Previously if the data at each of these paths were objects or arrays then these would be compared strictly, but now they are checked deeply. This brings the equality checking of object and arrays in line with the equality checking of Immutable.js Maps and Lists.