updated README; added Travis badge

Author: sommersoft

README.rst

@@ -11,6 +11,10 @@ Introduction
     :target: https://discord.gg/nBQh6qu
     :alt: Discord
 
+.. image:: https://travis-ci.org/adafruit/Adafruit_CircuitPython_MCP9808.svg?branch=master
+    :target: https://travis-ci.org/adafruit/Adafruit_CircuitPython_MCP9808
+    :alt: Build Status
+
 The MCP9808 is an awesome, high accuracy temperature sensor that communicates
 over I2C. Its available on `Adafruit as a breakout <https://www.adafruit.com/products/1782>`_.