add travis and mit license badge

Author: hathach

README.md

@@ -1,4 +1,6 @@
-# Adafruit_TinyUSB_Arduino
+# Adafruit TinyUSB Library for Arduino
+
+[![Build Status](https://travis-ci.com/adafruit/Adafruit_TinyUSB_Arduino.svg?branch=master)](https://travis-ci.com/adafruit/Adafruit_TinyUSB_Arduino)[![License](https://img.shields.io/badge/license-MIT-brightgreen.svg)](https://opensource.org/licenses/MIT)
 
 [TinyUSB](https://github.com/hathach/tinyusb) library for Arduino IDE. This library works with core platform that includes TinyUSB stack, typically you will see **Adafruit_TinyUSB_Core** inside core folder. Supported platform are: