Don't call pollServer from a BroadcastRecevier

Don't call pollServer from a BroadcastRecevier

LocalBroadcastRecevier and DynamicBroadcastRecevier used to call pollServer directly. Thus, processCommand was called from a BroadcastRecevier context, which broke some commands (e.g. SPEAK). Now, they call a new function, safePollServer, which calls pollServer from FonBotMainService.