blobs not supported

[javimoya]

all functions related to blobs that can be found on forceTK... are not available on forceng:
blob = function (path, fields, filename, payloadField, payload, callback, error, retry)
createBlob = function (objtype, fields, filename,
payloadField, payload, callback,
error, retry)
updateBlob = function (objtype, id, fields, filename,
payloadField, payload, callback,
error, retry)