Add submodules for narwhal, ojtest and browser.js

.gitmodules

@@ -0,0 +1,9 @@
+[submodule "External/narwhal"]
+	path = External/narwhal
+	url = git://github.com/tlrobinson/narwhal.git
+[submodule "External/browser.js"]
+	path = External/browser.js
+	url = git://github.com/tlrobinson/browser.js.git
+[submodule "External/ojunit"]
+	path = External/ojunit
+	url = git://github.com/280north/ojunit.git