Add Documentation for Android SDK, API 19

Signed-off-by: Paul Campbell <pcampbell@kemitix.net>
Add Samples for SDK API 19

Signed-off-by: Paul Campbell <pcampbell@kemitix.net>
Add Sources for Android SDK, API 19

Signed-off-by: Paul Campbell <pcampbell@kemitix.net>
README.md: remove duplicate entry

Signed-off-by: Paul Campbell <pcampbell@kemitix.net>
Add Google Play Billing Library

Signed-off-by: Paul Campbell <pcampbell@kemitix.net>
Add Google Play Licensing Library

Signed-off-by: Paul Campbell <pcampbell@kemitix.net>
Merge pull request #6 from kemitix/feature/additional-sdk-components

Feature/additional sdk components