Add statistics for fembers + balance

[joandrsn]

Specifically, I think it could be great with the following information in stregsystemet, but it's up to debate if it would be useful.

What I have in mind:

• How much balance fembers have, grouped by Active/Inactive
• How much deposited into stregsystemet within the last week/month
• How many active/inactive fembers there are
• How many new fembers this year (since July) - I also think it would be great to know how many fembers have been marked inactive in the last year, I don't think this is possible at the moment.
• If Allow user to cancel latest bought item #188 were to be implemented, a list of current active user with the highest number of cancelled sales (To prevent abuse of the feature).