replace mnm.js by node-gyp with bindings.gyp

... as per supported method described in latest docs http://nodejs.org/api/addons.html .

Add-on / native extension module builds OK in Ubuntu 10.04 and 12.04 with Node 0.8.23, 0.10.5 and 0.10.6. Note that build options for Mac OSX, OpenBSD and SmartOS are not yet tested.

The resulting add-on works fine with Node 0.10.5 and 0.10.6, but still segfaults in 0.8.23, as described in https://github.com/nearinfinity/node-shark/issues/1 .