Add new method for ObjectReader, to bind from JSON Pointer position

[cowtowncoder]

Reading a subset of a document, binding it, is quite possible to do already. For example by:

JsonNode tree = mapper.readTree(source);
JsonNode node = tree.at("/caller/1/name");
POJO value = mapper.treeToValue(node, POJO.class);

But it would be even more convenient (and, potentially, more efficient) to make ObjectReader find the JSON Pointer location using new (2.6) streaming filter, and bind directly from there.

Something like:

POJO value = mapper.reader(POJO.class)
    .at("/caller/1/name")
    .readValue(source);