gx update and fix code to use new Cid type

[kevina]

See ipfs/go-cid#71 for additional info.

Depends on:

• gx update and fix code to use new Cid type go-path#7
• gx update and fix code to use new Cid type go-unixfs#15

Which Depends on:

• gx update and fix code to use new Cid type go-bitswap#10
• gx update and fix code to use new Cid type go-block-format#14
• gx update and fix code to use new Cid type go-blockservice#5
• continuation of use string instead of struct backing go-cid#71
• gx update and fix code to use new Cid type go-ipfs-blockstore#15
• gx update and fix code to use new Cid type go-ipfs-blocksutil#2
• gx update and fix code to use new Cid type go-ipfs-chunker#4
• gx update and fix code to use new Cid type go-ipfs-ds-help#6
• gx update and fix code to use new Cid type go-ipfs-exchange-interface#2
• gx update and fix code to use new Cid type go-ipfs-exchange-offline#8
• gx update and fix code to use new Cid type go-ipfs-posinfo#2
• gx update and fix code to use new Cid type go-ipfs-routing#13
• gx update and fix code to use new Cid type go-ipld-cbor#40
• gx update and fix code to use new Cid type go-ipld-format#42
• gx update and fix code to use new Cid type libp2p/go-libp2p-routing#27
• gx update and fix code to use new Cid type go-merkledag#12
• gx update and fix code to use new Cid type go-verifcid#3

Please approve but do not merge. Depends on locally pinned hashes.