resourceloader: cache minified user and site modules

resourceloader: cache minified user and site modules

* Add support for a '/* @nomin */' annotation in ResourceLoader. If present in
  JavaScript or CSS, the code will not be minified or cached. This allows
  modules like the ResourceLoaderUserTokensModule to declare themselves unfit
  for minification / caching without requiring a complicated refactor.
* Make ResourceLoader::filter() static, at the cost of not having minifier
  errors in the ResourceLoader log bucket. (They will continue to be logged as
  exceptions, however).

Change-Id: Ic1d802ee20565e61046bfbd8fd209bc56a4cbd6c