refactored `User.create` in preparation for twitter compatibility (issue

src/user.js

@@ -10,29 +10,34 @@ var utils = require('./../public/src/utils.js'),
 	async = require('async');
 
 (function(User) {
-	
 	User.create = function(username, password, email, callback) {
-		username = username.trim(), email = email.trim();
-
-		// @todo use node-validator?
-		if(!utils.isEmailValid(email) || !utils.isUserNameValid(username) || !utils.isPasswordValid(password)) {
-			callback('Invalid email/username/password!', 0);
-			return;
-		}
-
 		var userslug = utils.slugify(username);
 
-		User.exists(userslug, function(exists) {
-			if(exists) {
-				callback('Username taken!', 0);
-				return;
-			}
+		username = username.trim();
+		email = email.trim();
 
+		async.parallel([
+			function(next) {
+				next(!utils.isEmailValid(email) ? new Error('Invalid Email!') : null);
+			},
+			function(next) {
+				next(!utils.isUserNameValid(username) ? new Error('Invalid Username!') : null);
+			},
+			function(next) {
+				next(!utils.isPasswordValid(password) ? new Error('Invalid Password!') : null);
+			},
+			function(next) {
+				User.exists(userslug, function(exists) {
+					next(exists ? new Error('Username taken!') : null);
+				});
+			},
+			function(next) {
 				User.isEmailAvailable(email, function(available) {
-				if(!available) {
-					callback('Email taken!', 0);
-					return;
+					next(!available ? new Error('Email taken!') : null);
+				});
 			}
+		], function(err, results) {
+			if (err) callback(err, 0);	// FIXME: Maintaining the 0 for backwards compatibility. Do we need this?
 
 			RDB.incr('global:next_user_id', function(err, uid) {
 				RDB.handle(err);
@@ -63,9 +68,7 @@ var utils = require('./../public/src/utils.js'),
 				RDB.set('email:' + email +':uid', uid);
 				RDB.set('userslug:'+ userslug +':uid', uid);
 
-					if(email) {
 				User.sendConfirmationEmail(email);
-					}
 
 				RDB.incr('usercount', function(err, count) {
 					RDB.handle(err);
@@ -86,7 +89,6 @@ var utils = require('./../public/src/utils.js'),
 				callback(null, uid);
 			});
 		});
-		});
 	};
 	
 	User.delete = function(uid, callback) {