[DEV] support bad json responses that to avoid app crashes
[DEV] support bad json responses that to avoid app crashes

- within ARUPDATER_Downloader_GetBlacklistedFirmwareVersionsSync

Change-Id: Idd9e8d6eb42720fe188701842705bec897ce82cf
Reviewed-on: https://gerrit.parrot.biz/50785
Reviewed-by: Djavan Bertrand <7232792b712c7d1777e4e988572ac52f60124955@parrot.com>

Parrot-Developers/libARUpdater,Parrot-Developers/libARUpdater,Parrot-Developers/libARUpdater