Minor cleanup:
https://github.com/stepio/jpasskit/issues/6
Default value for "voided" should be "null" instead of "false" to make it optional
https://github.com/stepio/jpasskit/issues/7
Update setter for "suppressStripShine" to set "null" instead of "false"
https://github.com/stepio/jpasskit/issues/8
Linking Android Apps to a Pass
https://github.com/stepio/jpasskit/issues/9
Linking Android Apps to a Pass: renaming + unit test
https://github.com/stepio/jpasskit/issues/9