Update flow syntax

[Brianzchen]

This change is all about maintaining the flowtype code.

• Update to latest version so that it can be maintained easier and also allows LSP mode
• Update flow config for best practice warnings including ambiguous-object-type which ensures as a library we explicitly define objects as exact/inexact for if flow types are exposed in the future
• Fix all flow errors from upgrading flow version, no logic has been changed
• Migrate from flow comment syntax to regular syntax and stripping with @babel/preset-flow. After upgrading there were syntax errors raised by flow in the dist file. Doing this removes the errors and makes the project easier to maintain
• All src files are now flow typed which will help in future flow exposure

@lencioni @jlfwong

[Brianzchen]

Added a new line to travis.yml. The example dir never ran npm install during the build which was fine because it's only imports were react and react-dom. But react-dom has since had it's definitions removed from flow and into flow-typed which caused errors during flow check.