[WIP] Userinfo stats

[Elanis]

As asked in #53, this PR adds more data to !userinfo command to display informations using stats module.

To do:

• [X] Get user total stats
• [X] Get user per month stats
• [ ] Get user per channel stats => Impossible atm, would need to change stats module
• [ ] Display user per month stats as an image

Current version: (WIP)