Team Umbraco stats optimisation

[glombek]

Optimise the Team Umbraco page to help with load times.

• Only load the stats once
• Update amCharts to latest
• Zoom graphs with a narrower timeframe to match current implementation
• Reload graphs on a timer (instead of reloading the entire page)
• Cache the grouped PRs server- and client-side to help reduce the load

(At Community Teams Virtual Visit)