Don't compile Node unless we really have to

At best, compiling a new version of Node means the request timing out and a 30 minute wait. At worst, it's been silently failing for me sometimes.

This fix will try to find a matching binary tarball from the node dist server. If it can't, it will download the source and compile like it did before. Rather than taking a half hour to compile, it now takes a second or two to download/extract.