Custom operation with pybitshares

Hi @xeroc ,
So, just wanted to use the blockchain as DB and wanted to store custom user data like email, bio...
After some finding I found custom operation plugin but don't have any direction, How to use it?
I looked into the JS library but that also not support the custom operations.

Does this library supports the custom operations?

首先定位 pybitshares 中用于构建 operation 和提交 transaction 的入口点，然后将其与 issue 中提到的 custom operation plugin 和 JavaScript library 进行比较。确定是否支持 custom operation，以及缺少哪些 API 或文档；当支持问题有明确且经过测试的答案，或已经达成一致的实现范围时，即表示完成。

由索引模型根据 Issue 内容生成。