v5 Checkpoint

[i-norden]

This is the bulk of the functional updates. Not quite finished but getting close. Builds but still need to fix some (most) tests.

• rename public.blocks to ipld.blocks.
• rename mh_key to cid.
• consolidate all sql stmts into a single place.
• combine ipld and cid retriever structs into a single struct. Originally these were separated because we used to first fetch a cid from Postgres directly, but then fetch the corresponding IPLD block through an ipfs.BlockService abstraction (which could be applied on-top of our DB, using ipfs-ethdb, or used on-top of an IPFS p2p block exchange. We now fetch everything from the local Postgres DB for performance reasons, in one trip where possible.
• rename node_type => removed; refactor to support.
• Moved some packages from geth to here, because as geth moves to v5 it no longer uses them (and this is now the only place that does).
• use ipld-eth-statedb backend for eth_call and relevant graphql endpoints.
• refactor to use the new (proper) uncle IPLD representation (no longer need to check ordering of returned headers).

TODO:

• Fix unit tests
• Rebase to 1.11.4

[i-norden]

This actually isn't so bad to review

[roysc]

LGTM as an incremental part of v5.

One revision - we can change the tag of the ipld-eth-db migrations container to v5.0.0 in the docker-compose.yml. It won't work until that tag is published, but it's not run on this branch anyway.

[i-norden]

Merging this, next PR will have the test fixes