SyncBot CLI Fixes

1) Initialize filesToSync to prevent an exception when there are 0 files to sync (bad path or files are up to date).
2) Add try/catch to the p4.Run command in GatherFiles to log errors created by the p4.Run command.
3) Remove check for P4PASSWD being set - Perforce will throw an exception before this.
4) Add global exception handling to Task to report exceptions rather than throw unhandled exceptions.