Fix Date Formatter failing when non en_US locale
Fix Date Formatter failing when non en_US locale

Summary:
For whatever reason, the format in crash logs is only valid when the locale is set to `en_US`. This means that if your system's locale is en_GB, then the date parsing will fail and crash log ingestion will fail

This corrects thius

Reviewed By: c-ryan747

Differential Revision: D26664162

fbshipit-source-id: 8d3e0eac5911a8e353b2809b2b59eb024a92218b

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