Fix/new api syntax

Hello!

Recently, Wit structurally changed their return to queries. As you can see on their website (https://wit.ai/docs/api#span-classtitle-verb-getmessage), the example shows that more than one outcome can be returned in an array. We also found a few other things in the gem that we thought could use tweaking. We added all the changes we made to the changelog.

Hopefully you find these changes helpful. Thanks for a great gem!

Best,
@PWehlin & @rohitahuja