add npm package "node_amf_cc"
use native AMF (de)serialization lib

* use egiantine's AMF library for (de)serialization of AMF messages
* adjust unit tests ("type" is a "magic" object property in AMF; see
  e.g. <https://github.com/timwhitlock/node-amf/pull/13>)
* adjust benchmark suite accordingly
remove npm package "amflib"
Merge pull request #24 from yelworc/native-amf-lib

switch to egiantine's C++ AMF lib