Buildserver update for ai2

Hi all,

Due to an issue where compiled Android apps would crash on versions of Android prior to 5.0, we have updated our buildservers with a patch that should fix the issue. If you have encountered crashes on startup of your apps for older Android versions, please recompile your apps and try again. Sorry for the inconvenience.

Evan W. Patton, Ph.D.
Lead Software Engineer, MIT App Inventor