BREAKING CHANGE: Refactoring the Tag API: use id for a specific tag

[huan]

Currently, we are using the tag string as the id of the tag itself.

However, it seems that in the Wechat system internal, every tag has an id, and we can rename a tag by change the string attached to that id so that all contacts/favorites with that id will be affected.

To be refactored.

[huan]

Update Apr 13

After reviewing the WeChat app on the phone, it turns out that the Tags of Favorite is not the same as the Tags of Contacts.

After that, I'm thinking that perhaps the current design of our Tag system is better, because we can focus on the Tag itself, do not care about whether it's from a Contact or a Favorite.