Report on partial-block nodes

[matthewdarwin]

Report on p2p and api nodes that don't have complete history, rather than reject them entirely.

For p2p, need to add checks that block 1 exists.

Also need to check have reasonable set of blocks, say 1m backwards from now.

[str]

today - 1 month, is a good start

[Rossco99]

172,800 blocks are produced / Day .. 1,209,600 blocks / Week .. a rolling recent 6 Million block.log is reasonable in my opinion, which gets us to around a month of currency.

[Rossco99]

Thinking more on this threshold.. Maybe 6 Months is a good place. A rolling 36Mil Blocks.