TODO: different level of browser support

Maybe not now, but before alpha release.

Add options for user to select the level of browser support. The list of options is to be decided.

Default to evergreen browsers. One good thing is it does not need to transpile async/await on latest browsers. Transpiled async/await is a performance killer.
The lowest we can go is IE11. It will require few polyfills and use special Aurelia 2 build.

The issue names no file, entry point, or test. Start by reviewing the scaffolding project's setup flow and how browser targets are currently selected or built. First decide the supported target options and the alpha-release scope; done means the browser-support choices and their defaults are specified clearly enough to implement and verify.

Written by the indexing model from the issue text.