## Motivation
The code before this PR had serveral issues:
1. Context uses reference identity to determine when to re-render, there are some gotchas that could trigger unintentional renders in consumers when a provider’s parent re-renders.
https://reactjs.org/docs/context.html#caveats
2. `setState` should use the reducer pattern in this example to make sure clicks are not swallowed by react batch.
* form handler example: Update deps and fix build from dep update
* Ran lint error fixers
* Fixes errors that occur when commit occurs
* Commit linter fixes
…aces (home and about pages). This makes it the example more clear and why someone might want to use _app.js in the first place. Also, added a button on the about page that allows for passing and arbitrary value from the about page to the context provider. I disagree with the naming convention of calling the class CounterProvider. It includes both a Provider and Consumer so it should have some name that covers both. Maybe it should be called CounterContext but I did not change that. I've seen other examples of the same naming conversion so figure I'm the odd duck here (still think it's wrong no matter how many people do it).
