updated README; added Travis badge

Author: sommersoft

README.rst

@@ -10,6 +10,10 @@ Introduction
     :target: https://adafru.it/discord
     :alt: Discord
 
+.. image:: https://travis-ci.org/adafruit/Adafruit_CircuitPython_CircuitPlayground.svg?branch=master
+    :target: https://travis-ci.org/adafruit/Adafruit_CircuitPython_CircuitPlayground
+    :alt: Build Status
+
 This high level library provides objects that represent CircuitPlayground hardware.
 
 .. image :: /_static/circuitplayground_express.jpg