Unable to resolve path to module 'underscore.string/titleize' import/no-unresolved

[mythmon]

In CI build 1529 on master, this error came up:

/app/code/recipe-server/client/control/actions/FilterActions.js
  12:22  error  Unable to resolve path to module 'underscore.string/titleize'  import/no-unresolved

The build in the PR also had the error, but the error was not reported because of #481.

I don't think we have the underscore library installed that can support this sort of piece-meal usage. I also didn't find titleize in the version of underscore installed in recipe-server.

[mythmon]

This builds fine in Webpack, which makes me think this is more of a linting issue than a packaging issue. But I don't actually understand how it could work either way.

[mythmon]

Since Andy is doing onboarding this week, I'll take this.