[bitshares/bitshares-core] get to_id from to_account instead of get_account_id() (#1242)

@RichardWeiYang Thank you for the contributions to BitShares development. I hope to connect with you directly about the `Community Claims` compensation available through the [BitShares Core Team Worker Proposal](https://www.bitshares.foundation/workers/2018-03-bitshares-core). You may reach me on Telegram or WeChat: ryanRfox

Thank you.