Improve statistics data collector

[rodrigok]

To be able to show a dashboard of server usage over the time with statistics like listed bellow we need to improve our data collector to store more data points and aggregate them correctly.

List of data we could show

• Most active channels
• Most active users
• Average time usage per channel
• Average time usage overall
• Number of users over time
• Most busy time
• Active users per day, week and month
• Average messages per channel
• Average messages per day and month

And more...

Some ideas could be found in this issue too:
#3824

[janrudolph]

@rodrigok We have enhanced the Rocket.Chat statistics in order to calculate Daily Active, Weekly Active and Monthly Active Users. Therefore we added the number of views and writes per user and hour. If you are interested in the implementation, please have a look at our PR assistify#264

[rodrigok]

@janrudolph awesome, I'll take a look soon, thanks