Fix spawns against Node

For example some code tries to run -e against the binary but that fails
since we inject our entry file every time the binary is invoked.

Fixes #932.

main.js

+// Once our entry file is loaded we no longer need nbin to bypass normal Node
+// execution. We can still shim the fs into the binary even when bypassing. This
+// will ensure for example that a spawn like `${process.argv[0]} -e` will work
+// while still allowing us to access files within the binary.
+process.env.NBIN_BYPASS = true;
+
 require("../../bootstrap-amd").load("vs/server/src/cli");