Take care of lint warnings.

The library only has three lint warnings left, for app icons and API versions. The icon for the sample app can be updated to use the current SDK default icon (which has a hires, but no lores, version) and the other warnings are not helpful so they can be supressed. With these changes, running lint on the entire project will come up with zero warnings so that, going forward, a lint warning that appears will be a good indicator of something fishy.