Custom importers shouls be able to easily add .plugin() statements to main.js

[JeroenVinke]

trafficstars

I'm submitting a feature request

One of the common use cases for custom importers is to add .plugin() statements to main.js. We could expose a service to custom importers that can do this. It is quite tricky to patch main.js due to the irregular format of main.js

[RWOverdijk]

It might be nice to use aurelia config for this. We use it in our applications. And I use it in the plugins we have. It's optional, but a (I think) nice standard. It allows merging of configs and makes it super easy to add configs for your plugins.