Make Shadows package configurable.
Merge pull request #1391 from kriegfrj/configure-shadows-package

Make Shadows package configurable
Update asset/resource resolution

Make asset and resource path resolution consistent with manifest
resolution. Use system property values before default values.

This allows merged assets and resources paths to be specified in system
properties the same way the AndroidManifest.xml path is specified.
Merge pull request #1400 from jle/split-res-asset-resolution-from-manifest

Update asset/resource resolution