[db] removes commented out lines that were moved to HostMonitor
[db] adds an Error message if enable_statistics is not set to true
[db] updates TopicProfile with proposed additions to TopicStatistics
[db] adds delivered_msgs capabilities to host_profiler
[db] improves some of the printouts
[db] changed TopicProfile stddev to std like Node and Host profiles
implements combined std information, reduces amount of math needed to be
performed if you only have one message
[db] removed unnecessary checks for empty values since they are
protected by the if statement
fixes bug with host cpu usage that was causing the buffer to never
refresh
[db] removes unpopulated fields from NodeProfile message