Update node-expat dependency for Windows

node-expat began using node-gyp over node-waf around version 1.6.1 or 2.0.0. node-waf is not and will not be compatible with Windows from what I've read. I've tested mediainfo with 2.0.0 and all is well so far.
Merge pull request #1 from jholloman/patch-1

Update node-expat dependency for Windows