Support including modules that don't have an extension.

This way, require("/foo") will work if there is a "foo.js", or a file named
simply "foo" with no extension.

lib/module.js

@@ -142,7 +142,8 @@ function findModulePath (id, dirs, callback) {
     path.join(dir, id + ".js"),
     path.join(dir, id + ".node"),
     path.join(dir, id, "index.js"),
-    path.join(dir, id, "index.node")
+    path.join(dir, id, "index.node"),
+    path.join(dir, id)
   ];
 
   var ext;

test/fixtures/foo

@@ -0,0 +1,2 @@
+
+exports.foo = "ok"

test/simple/test-module-loading.js

@@ -103,6 +103,9 @@ debug("load modules by absolute id, then change require.paths, and load another
 var foo = require("../fixtures/require-path/p1/foo");
 process.assert(foo.bar.expect === foo.bar.actual);
 
+assert.equal(require('../fixtures/foo').foo, 'ok',
+  'require module with no extension');
+
 process.addListener("exit", function () {
   assert.equal(true, a.A instanceof Function);
   assert.equal("A done", a.A());