Support iisnode using named pipes as PORT value

Port can't be number checked to support iisnode. Using a parseInt()
or number isNumber function won't work if we want to support iisnode
which uses named pipes for ports (ex. \\.\pipe\mypipe)

lib/executor.js

@@ -115,7 +115,9 @@ function setPort(app, instructions) {
     process.env.npm_package_config_port,
     app.get('port'),
     3000
-  ], isFinite);
+  ], function(p) {
+    return p != null;
+  });
 
   if (port !== undefined) {
     var portType = typeof port;

test/executor.test.js

@@ -417,10 +417,11 @@ describe('executor', function() {
       assert.equal(app.get('port'), 3000);
     });
 
-    it('should ignore non-numeric port values in ENV', function() {
-      process.env.PORT = '123invalid';
+    it('should respect named pipes port values in ENV', function() {
+      var NAMED_PORT = '\\.\\pipe\\test';
+      process.env.PORT = NAMED_PORT;
       boot.execute(app, someInstructions({ config: { port: 3000 } }));
-      assert.equal(app.get('port'), 3000);
+      assert.equal(app.get('port'), NAMED_PORT);
     });
   });