Add statistics to the admin

[vohmar]

We need to add statistical data to the admin interface
Implement the same statistics that are presented on the internet.ee web page: https://www.internet.ee/abi-ja-info/statistika
in admin present the stats in numbers/tables

Core data:

• domain count current
• domain count change in previous month and same month a year before - count + percentage
• domain renewal rate during the previous 12 months
• paid operations (new registration + renewals) count in previous month and same month a year before - count + percentage
• new registrations in previous month and same month a year before - count + percentage
• renewals in previous month and same month a year before - count + percentage
• deletions in previous month and same month a year before - count + percentage

additionally we could collect monthly data in the table and plot the chart to spot the trends

as an added bonus would be having a market share info - we could get that from CENTR stats