Remove stats resolver

[0xERR0R]

Remove stats resolver with statistic aggregation. database query logging (#258) with new Grafana dashboard (#265) should be used instead. This would allow to save some memory, since the aggregation is in-memory only.

Following should be removed:

• statsResolver
• stats package
• Signal handler to show the stats on the console
• dependency to go-pretty (tables for CLI)
• documentation