Add Google Charts for monthly summary

[jakubgarfield]

https://developers.google.com/chart/interactive/docs/quick_start

[arturoromeroslc]

Would you like some help with this? Do you have a branch up as a WIP?

[jakubgarfield]

No branch, just didn't have a chance to work on it and been quite happy with using the web view in sheets so far.

Feel free to grab that one and we can merge it if you keen to finish it.