Use new GWT options

I think would allow us to develop everything in the same package and use the new `excludeJsInteropExport` to make smaller builds.

From https://groups.google.com/forum/#!topic/google-web-toolkit-contributors/jAWXDG492D8:
> Support filtering JsInterop types for export, with whitelist/blacklist and wildcards. The -generateJsInteropExport flag is still used to enable the feature, but -includeJsInteropExport and -excludeJsInteropExport now exist to specify packages with optional * wildcards. Later arguments and patterns override earlier ones.

The issue names no files or tests; start by locating the GWT build configuration and reviewing the linked Google Groups discussion for the new export options. Done should mean the package uses the include/exclude settings and produces smaller builds without losing required exports.

Written by the indexing model from the issue text.