v0.4.0

Thanks for using opentok-react!

Changes

• Add error and completion handlers (thanks to @Fofir)
• Add preloadScript (thanks to @ziad-saab)
• Fix bug where insertDefaultUI wasn't respected (thanks to @pronebird)
• Add tests configured to run in Travis CI
• Add yarn.lock file
• Prepare project for open source contributions

Please feel free to open issues or submit pull requests if you find a problem or would like a new feature.