Please create api for get_account_votes

[tngflx]

get_account_votes is a much needed feature for checking the latest post that an account upvoted. This will be helpful for others who want to keep track of their upvoted posts. I tried client.database.call('get_account_votes',['someone']) resulted in timeout in fetching data. It seems that the data is too big to retrieve? But with steemjs worked perfectly