Add common handling of broadcasts exceptions into SO

[Vladimir Kamarzin]

SO uses operations bundling and own handling of broadcast errors. BitsharesOrderEngine.retry_action() has handling of various errors. Need to refactor retry_action() to be a decorator, so any method may which broadcasts something may use it for intelligent error handling.

[Vladimir Kamarzin]

Decorator is not good for this, we don't need to wrap whole functions, let's continue to use retry_action() idea.