Fix rake task crash when not using default app (so there is no pem file)
Fix rake task crash when not using default app (so there is no pem file)

PRX/apn_on_rails,BreakthroughBehavioralInc/apn_on_rails,timsu/apn_on_rails,bnigro/apn_on_rails3,meer-online/apn_on_rails,STRd6/apn_on_rails,digisight/apn_on_rails,mbartmann/apn_on_rails,logansease/apn_on_rails,jwang/apn_on_rails