Optimistic Loading/Verification (signatures)

[zachferland]

The ability load entries without verifying their signatures. This has two dimensions, one is to optimistically accept entries while loading and then verify after, the second is to not verify entires we already have seen and verified in the past.

The second already discussed a few months ago, the difficulty being from orbitdb/3boxs perspective you cant tell if ipfs just got a given block locally or from the network. It may be possible to tie these to together in some form, just no interfaces for that right now. It may be simpler to just have some "has seen" cache and it may be reasonable to use some space-efficient member test like a bloomfilter, although false positives less ideal here.

Need to specify further to breakdown in to separate issues. May need some interface hook from orbitdb or the identity provider may be enough.