Added ability to share image via demo app and attach it automatically to currently active event (if it exists).
Added support for async Future calls via Guava and added several tests. Updates #10, #28.
Added tracking header. Updates #6.
Modified exchange simple demo app to use Futures. Updates #12, #10.
Added more comments to the code that works with SDK.
Updated and created async Java-based tests for the SDK.
Removed caching for NavigationProperties.
Updated tests. Added license headers.
Updated common tests and added async Android-based tests. Updates #28, #10.
Merge pull request #47 from OfficeDev/exchange_async

Merged async Guava based logic into dev.