Supporting NODE_PATH

This is related to #6.

When Electron initializes the Module paths, it will grab everything from `NODE_PATH` and merge it with the user's home dirs.

However, at some point in execution, this `Module.globalPaths` is mutated and replaced with a new set of paths pointing to electron globals so that `require('electron')` will work. It is unclear where this mutation is happening, and at what point we need to re-patch the `Module.globalPaths` array to fix this.

To recap, these two features are broken right now:
- `NODE_PATH` is not respected
- `.node_modules` and `.node_libraries` in home dir is not respected