Now that Raven is bundled with webpack, it's not available in the global context, so require it and configure it within the init module.
I struggled to figure out how to expose the raven-js module as a global, as all the combinations of `externals` and `ProvidePlugin` only applied to webpacked modules, not the global window. The correct way to do it seems to be exports-loader but that looked rather hacky and hard to understand.
This should allow us to define and update our dependencies more easily (via npm) as well as reducing the number of requests.
Additionally, when we add common packages this will avoid the issue after deploys where a user may get a cached HTML page, but new Javascript, leading to the dreaded blank page because the browser didn't download all dependencies.
Using mangle with UglifyJS also made the total file size for the common chunk bundle smaller than the current total for all of our external/polyfill scripts (1.18MB vs 1.55MB).
This doesn't solve the issue of making it crawlable in other languages, but it does allow the title to be translatable for user parsing (and accessibility)
