27.on blur event

[federiva]

Have you read the Contributing Guidelines?

Issue #27

Changes description

Addressing aforementioned issue

• Added onBlur event in the reactable-extras.js
• Updated the inst/examples/demo/reactable-inputs/app.R
• Added e2e test for this component
• Fixed a missing devtools::load_all() in the package.json script starting the app as it was crashing
• Updated README and news.md

How to test

1. You can run the updated example in the README.md
2. Run e2e tests