added nodejs makefile, updated all bindings, updated const generator for nodejs, ruby and python

bindings/nodejs/Makefile

+# Python binding for Keystone engine. Nguyen Anh Quynh <aquynh@gmail.com>
+
+ifndef BUILDDIR
+OBJDIR = ./build
+else
+OBJDIR = $(abspath $(BUILDDIR))/obj/bindings/nodejs
+endif
+
+.PHONY: gen_const install clean
+
+gen_const:
+	cd .. && python const_generator.py nodejs
+
+install:
+	npm install ./
+
+clean:
+
+check:
+	node sample.js
+