adding zone id for computing server side latencies
  - Zone id is an optional header in the REST request
  - if the request is from same zone, the server side latencies are
    recorded
adding logic to filter expired requests
- Renaming connectionStats and ConnectionStatsHandler classes
- Processing code review comments for the commit
4bdae66753d1dd8ee5de52563fda206e038cf19f
- removed tracking for getversion