Fixed issue related to real-time monitoring getting stuck when there is delay in response from meter.
This was because multiple monitor_and_Alert threads were running in parallel and hogging a mutex which was
preventing the processing of Wait_for_Req(). Now in the Monitor_and_Sample thread, before a monitor_and_Alert thread is started, a check is made to
ensure that there are no previously created invocations of this thread. If exist, then a new thread
is not started.
Also changed the location of mutex locking in wait_for_req() thread so that if a series of messages are received
from IS, they are processing together.
Merge branch 'master' of https://github.com/tharianjk/FieldServer