Removes need to set NODE_PATH environment variable

Solution: create a symlink to `your-project/node_modules` in the
`STATIC_PATH`, which lives in the Karma tmp directory.

also rewrote some paths to use `path.join` as it (theoretically)
provides better Windows support.
update package.json for 0.9.2-2 of nodewebkit installer

requires node 0.11.9 or greater
updating to nodewebkit 0.10.0 against NodeJS 0.11.13 (+1 squashed commit)