Migrate from Bower to Yarn

[jscharf]

During the Travis CI builds, the following line is being displayed

npm WARN deprecated bower@1.8.2: ...psst! Your project can stop working at any moment because its dependencies can change. Prevent this by migrating to Yarn: https://bower.io/blog/2017/how-to-migrate-away-from-bower/

I propose that we follow the instructions laid out in the link above and migrate from Bower to Yarn.

[juwara0]

@jscharf - Thank you for filing this issue!

This will be migrated to node 8 with npm 5. It is on my list of work currently underway when I get to this repo.

It is also on my radar that we migrate packages from bower.json to other ways of importing.