OHM-444 Prevent polling when last transaction req is pending
OHM-444 Prevent polling when last transaction req is pending

This commit adds a flag (lastPollingCompleted) and polls the next transaction only when the last polling request is completed. if not completed, the current poll is skipped (i.e. waits for another 'pollPeriod' before trying again).

jembi/openhim-console,jembi/openhim-console,jembi/openhim-console