Make BackRefBuilder's constructors package-protected
BatcherImpl field can be final
Make provider.Selection a parcelable class
Make provider.Projection a parcelable class
Make ProviderAction.Update parcelable
Make ProviderAction.Delete a parcelable
Make ProviderAction.Query parcelable
Make ProviderAction.Insert Parcelable

This required a change in Batcher, since it's comparing stuff by identity
Base equals()/hashCode()/toString() implementation for ProviderAction
Add tests for checking if Parcelables are parceled correctly