Avoid validator jailing on chain halts

[mdyring]

Describe the bug
After a multi-hour chain halt, any validator who is not signing the first block at recovery will be jailed. This is undesirable as many of these might be trying to recover and will now have to wait for the minimum jailing duration.

Expected behavior
Open for discussion. But:

• If there is more than (say) 1H between two blocks, it could make sense to reset the "missed block" state.
• Consider lowering minimum jailing duration as well.

[mdyring]

@haasted I suggest we close this issue and instead:

1. Integrated Use cosmos sdk upgrade module #27 to ensure coordinated and fast upgrades
2. Increase downtime_jail_duration to 24H. This also addresses the complaint from many validators that 1H is not enough to recover a validator.

[haasted]

Both suggestions were addressed with the emoney-3 upgrade.