Need some trusted time servers among our PCs.

### Step 1: Please describe your environment

* ZeroNet version: 0.6.5 r3340
* Operating system: Ubuntu 16
* Web browser: tor-browser
* Tor status: always
* Opened port: no
* Special configuration: ____

### Step 2: Describe the problem:

Refer to : https://github.com/HelloZeroNet/ZeroMe/issues/115

I noticed a strange phenomenon today while commenting on the post in ZeroMe.

Another guy make a comment just now, and I read it and make a next comment following him, but my comment popped up under his comment. I deleted mine, and made another again, but it still goes under his one. I thought he hacked something or what, but I decided to wait 10 seconds and made another one only to fail. At last I could see my new comment above his one after around 40 to 50 seconds.

What was happened?

@HelloZeroNet : Since there is no central computer involved in ZeroNet the timestamp is added by the sender's computer. So if yours or the sender's computer time is out of sync, then it could break the order.

#### Steps to reproduce:

1. One PC make a comment on ZeroMe or something.
2. Within a second or more, another PC with the system time 30 seconds or more shifted backward from the above PC makes a comment on the same post as the above.
3. The above time shifted PC's comment stays under the the first PC's comment for about 30 seconds even though he deletes his comment and make again within 30 seconds.
4. After the amount of the shift time, it will be placed over the first comment if at least he made a new comment after 30 seconds the first guy did.

#### Observed Results:

* What happened? This could be a screenshot, a description, log output (you can send log/debug.log file to hello@zeronet.io if necessary), etc.

Refer to the above paragraph I described.

#### Expected Results:

* What did you expect to happen?

We need to appoint some trusted time servers among the decentralized PCs, don't we? Have them be chosen by voting. Predefined upvotes to downvotes ratio will switch off some of them or switch on others of them.

まず、参照されている ZeroMe issue #115 を読み、システムクロックがずれているシナリオを使って、手順に記載されたタイムスタンプの順序付けの挙動を再現してください。実装ファイルもエントリーポイントも特定されていません。作業が完了するのは、提案されている trusted-server または投票モデルを含め、分散化された PC 間のクロック同期に対する具体的で合意されたアプローチが扱われた場合に限ります。

索引モデルが issue の本文から書いたものです。