Add `pin` option to dag.put

[joeltg]

Right now you can stick a boolean pin property in the options argument to ipfs.add (and addReadableStream, etc), but there's no equivalent for ipfs.dag.put. This is awkward if you want to selectively pin or not pin your IPLD nodes and amounts to two-step ipfs.dag.put(object, options).then(cid => shouldWePinThis && ipfs.pin.add(cid.toString()) construction.

Not sure if this is the appropriate place to raise this issue but thought I'd bring it up here.

[alanshaw]

This was implemented in ipfs/js-ipfs#2521