dag api: get examples

[jbenet]

Example: ipfs.dag.get

var IPFSAPI = require('ipfs-api')
var ipfs = IPFSApi('/ip4/127.0.0.1/tcp/5001')

// given an object such as: 
//
// var obj = {
//     "a": 1,
//     "b": [1, 2, 3],
//     "c": {
//         "ca": [5, 6, 7],
//         "cb": "foo"
//     }
// }
// 
// ipfs.dag.put(obj, function(err, cid2) {
//     assert(cid == zdpuAkxd9KzGwJFGhymCZRkPCXtBmBW7mB2tTuEH11HLbES9Y)
// })

function errOrLog(err, result) {
    if (err) console.error('error: ' + err)
    else console.log(result)
}

ipfs.dag.get('zdpuAkxd9KzGwJFGhymCZRkPCXtBmBW7mB2tTuEH11HLbES9Y/a', errOrLog)
// Returns:
// 1

ipfs.dag.get('zdpuAkxd9KzGwJFGhymCZRkPCXtBmBW7mB2tTuEH11HLbES9Y/b', errOrLog)
// Returns:
// [1, 2, 3]

ipfs.dag.get('zdpuAkxd9KzGwJFGhymCZRkPCXtBmBW7mB2tTuEH11HLbES9Y/c', errOrLog)
// Returns:
// {
//   "ca": [5, 6, 7],
//   "cb": "foo"
// }

ipfs.dag.get('zdpuAkxd9KzGwJFGhymCZRkPCXtBmBW7mB2tTuEH11HLbES9Y/c/ca/1', errOrLog)
// Returns:
// 6

[daviddias]

The difference here from what we have is that we expect the arguments to be dag.get(cid, path, callback), where cid is an actual CID object and path is the string you want to search through.

I can add support for this way too.

[daviddias]

The other difference is that the result has two properties:

{
  value: <the last resolved value>
  remainderPath: <the path missing to be resolved, if any, if not, empty string>
}

[daviddias]

Added these examples (modified a little to respect the actual API) on #123