Production Readiness

[pablofullana]

The ability to:

• Create a richer config file #19
• Allow overriding RPCs #45
• Crash recovery #46
• Manage keys for the implementers #20
• Support sendings logs to a log aggregation service #47
• Enable a Solver instance to listen many chains #55
• Add support for sending ETH/native token #58

[lmcorbalan]

@pablofullana @tmsrjs @fernandomg
I think we should have a way to verify that filling an intent would work in both sides, mostly in the origin side were the filler is paid back.