support $ cnpm sync [moduleName1 moduleName2 ...], fixed #10

```
$ bin/cnpm sync urllib connect redis
Start sync ["urllib","connect","redis"].
logurl: http://cnpmjs.org/sync/urllib#logid=1493
[2013-12-14 02:02:09] user: dead_horse, sync urllib worker start.
[2013-12-14 02:02:10] [urllib] start...
[2013-12-14 02:02:10]   [urllib] all versions are exists
[2013-12-14 02:02:10] [urllib] synced success, 0 versions: 
[2013-12-14 02:02:10] [done] Sync urllib module finished, 1 success, 0 fail
Success: [ urllib ]
Fail: [  ]
logurl: http://cnpmjs.org/sync/connect#logid=1494
[2013-12-14 02:02:13] user: dead_horse, sync connect worker start.
[2013-12-14 02:02:14] [connect] start...
[2013-12-14 02:02:14] [connect] synced success, 0 versions: 
[2013-12-14 02:02:14]   [connect] all versions are exists
[2013-12-14 02:02:14] [done] Sync connect module finished, 1 success, 0 fail
Success: [ connect ]
Fail: [  ]
logurl: http://cnpmjs.org/sync/redis#logid=1495
[2013-12-14 02:02:17] user: dead_horse, sync redis worker start.
[2013-12-14 02:02:18] [redis] start...
[2013-12-14 02:02:18]   [redis] all versions are exists
[2013-12-14 02:02:18] [redis] synced success, 0 versions: 
[2013-12-14 02:02:18] [done] Sync redis module finished, 1 success, 0 fail
Success: [ redis ]
Fail: [  ]
Sync all packages done, successed: ["urllib","connect","redis"], failed: []
```