WIP: added group stats api, added `team` table

1. We need group stats, like a weekly/daily/monthly stats for each team (core, blueflood .etc)
  Currently, we only have a generic history which is extracted directly from database, that looks bad.
  Group stats should make everyone's status more clear and easier to read.
2. In order to accomplish ^, a team table is necessary .

WIP: need to work on the UI part to put the stats on html page..not just plaintext