Fix implode trailing comma in logging
Fix implode trailing comma in logging

Summary: This was resulting in `NSArray[foo, ]` instead of `NSArray[foo]` by adding a trailing comma in all cases

Reviewed By: jbardini

Differential Revision: D30044360

fbshipit-source-id: 26f29fd0a4f38bce71e544c36f51ff23d46ec728

facebook/FBSimulatorControl,facebook/FBSimulatorControl,facebook/FBSimulatorControl,facebook/FBSimulatorControl,facebook/FBSimulatorControl