Added param() with default value

lib/express.core.js

@@ -129,6 +129,10 @@
                this.response.headers[name]
     },
     
+    param : function(key, defaultValue) {
+      return this.request.uri.params[key] || defaultValue
+    },
+    
     /**
      * Return the contents of a function body.
      *
@@ -190,11 +194,11 @@
 })()
 
 get ('/users', function(){
-  return 'List of users'
+  if (user = param('user')) return 'User: ' + user
+  else return 'List of users'
 })
 
 get (/foo(bar)?/, function(){
-  dump(captures)
   return 'test'
 })