Adds new/merge rate to reviewers information

Adds more per day stats:
  - Changes with at least one patchset active in the time period
  - New changes uploaded
  - Changes merged
  - Changes abandoned
  - Changes left in WIP
Estimation of queue growth based over the time period

Change-Id: Idbedc70c19db215e627e047785238c5dc94fd4ea
Merge "Adds new/merge rate to reviewers information"