Adding /stocks response

Adds /stocks response that generates a quote from Robinhood and guesses the most relevant news from Yahoo using NLP sentiment analysis.

Production Release

Production release! Feel free to use Slash-Coins in your favorite chat platform.

• Slack support for /coins and /version
• HipChat support for /coins and /version
• Test plan with build verification c/o Travis: https://travis-ci.org/lockefox/slash_coins
• Build plan with Docker c/o https://www.revsys.com/tidbits/optimized-python/
• Docs c/o ReadTheDocs http://slash-coins.readthedocs.io/en/latest/

Currently deployed on https://lockefox.pythonanywhere.com/ for easy public use.