Support for node-webkit >= 0.9.2 (nw-gyp)

Due to a lot of changes in V8 used in node 0.11 & 0.12 support was made
using Nan to make it an easier implementation across versions. Tested
with nw-gyp on mac+windows (node-gyp with node >= 0.11 doesn't work)
Update to latest nan and fix compile errors

As I have zero experience with writing v8 code, I could have
totally borked everything.... will have to try it out later
when I have access to the apple remote hardware (since I know
the client stuff works with older lib code)
Update install.sh to build for nodewebkit if necessary
Rename asV8Exception to throwAs* to be clearer; resolve warnings
Merge branch 'dhleong/Node-0.11.13'