Make it easier to override default module rules in webpack-widget config

[clpetersonucf]

Right now there's no easy way to override the rulesets for a given pattern, ex:

rules = [
    {
        test: /\.js$/,
        loader: 'some-loader'
    }
]

Overriding the default rules for the pattern matching JS files would require copying over significant chunks of the default webpack-widget config into the webpack config for an individual widget. Instead, we can create default definitions for individual rules, allowing them to be more easily overridden by widgets based on their needs, like so:

module: {
    rules: [
		rules.loaderDoNothingToJs,
		rules.loaderCompileCoffee,
	]
},

[clpetersonucf]

This same update ought to be applied to the plugins section as well. The same formatting is used to clean, copy, and zip the contents of the build directory, but making changes to any of the steps requires them to be re-appended to the end of the plugins array, which is sloppy.