Fix live reload not working when using main.js (unminified) in index.html

[kellymilligan]

During development it's helpful to include the non-minified main.js in index.html. The middleware only watches for changes to main.min.js to run the build() step.

This adds main.js to the middleware check, and also passes whether the min version was requested through to build() as an argument, returning the appropriate bundle. Still logs out bytes based on the minified size.