Add shims to the React View Editor

:game_die: WIP :game_die:

If there are other parts of the API that break please respond to this issue with the package and the API it relies on.

### EditorView
* [ ] `overlayer` div and outlet are missing (breaks abe33/atom-color-highlight)
* [ ] `underlayer` div and outlet are missing (breaks richrace/highlight-selected)
* [ ] `scrollView` outlet is missing.
* [ ] `getModel` is missing. 
* [ ] `getFontSize` is missing. 
* [ ] `buildLineElementsForScreenRows` 
* [ ] `renderedLines` (breaks smashwilson/merge-conflicts)
* [ ] `getFirstVisibleScreenRow` and `getLastVisibleScreenRow` (breaks smashwilson/merge-conflicts)
* [ ] `lineElementForScreenRow` (breaks smashwilson/merge-conflicts)

### Gutter
* [ ] `getLineNumberElement` is missing (breaks dotcypress/coffee-lint)

Based on feedback from @abe33 and @smashwilson and anything I've run into personally.
Closes #2428