Improve the robustness of startLoginServerLogWatcher and stopLoginServerLogWatcher

[adamkorynta]

Based on feedback in PR: https://github.com/USACE-WaterManagement/cwms-logging/pull/2/files#diff-73bdb227d3042d65b857c09e306f8a51f78476f39d91bfedac01c5cfaf0c90b9

Need to add python process management instead of relying on the fragile pid written to disk.

Needs to gracefully exit the python process instead of terminating via kill.

[adamkorynta]

Likely need to add a SIGTERM and SIGINT handler:

def exit_gracefully(signum, frame):
    logging.info('Exited')
    exit(0)

signal.signal(signal.SIGTERM, exit_gracefully)

[rma-psmorris]

We might want to look at more than just process start/stop as understanding process status is also useful. Are there Python frameworks that do daemon process management that we could utilize?