Summary:
By declaring the properties first, before using them in the scripts, you no
longer get an exception if you fail to specify them.
You can now build artifacts or run tests without specifying your bintray
password, which is probably what you want.
Reviewed By: emilsjolander
Differential Revision: D4913103
fbshipit-source-id: 8787af8973cebb84cd59e18c63a3a9f28e0ec348
