What is the feature you want to add?

• add storage for additional information about instance added by user on console.

Why do you want to add this feature?

• issue: 权重设置、控制台对实例元数据的编辑结果持久化 #790

How to implement this feature?

• 1. database struct design (mysql) for additional instance info.
• 2. Create table and related cache for additional instance data #1262.
• 3. merge instance data cache from user and instance.
• 4. auto-clean job for instances no longer exist.
• 5. add support for boltdb data storage.