Minimize test work

This branch does a couple of things.

1. It fixes runtime errors caused by duplicated/overlapping inclusion of libraries in the main apk and the test apk.  The test apk should only include test-specific content (classes, resources, libraries)
2. It skips proguard on the test project altogether.  Given (1), the need to run proguard on the test project is pretty dramatically reduced.

With this branch, I'm finally able to successfully run some basic `ProviderTestCase2` stuff from sbt.

The downside:  It's a little bit hacky (note the use of the `skipApkLibDependencies` key).