Use a template for samples/source.properties so that it automatically
picks up the current platform API level.
Also merges 52feec594a
("Update rev numbers of SDK packages.")
Change-Id: I89574842d2b0290cc6cf454f82a3721644cae0f0
Adding a new folder in development/samples is not enough to have it be packaged with the SDK. Make sure to edit development/build/sdk.atree to add the sample to the SDK build.