Merge pull request #25 from gr8shivam/patch-1

Added CodeCov Badge

README.md

@@ -3,6 +3,7 @@
 [![Travis Badge](https://travis-ci.org/sendgrid/smtpapi-python.svg?branch=master)](https://travis-ci.org/sendgrid/smtpapi-python)
 [![Email Notifications Badge](https://dx.sendgrid.com/badge/python)](https://dx.sendgrid.com/newsletter/python)
 [![Twitter Follow](https://img.shields.io/twitter/follow/sendgrid.svg?style=social&label=Follow)](https://twitter.com/sendgrid)
+[![Codecov branch](https://img.shields.io/codecov/c/github/sendgrid/smtpapi-python/master.svg?style=flat-square&label=Codecov+Coverage)](https://codecov.io/gh/sendgrid/smtpapi-python)
 [![GitHub contributors](https://img.shields.io/github/contributors/sendgrid/smtpapi-python.svg)](https://github.com/sendgrid/smtpapi-python/graphs/contributors)
 [![MIT Licensed](https://img.shields.io/badge/license-MIT-blue.svg)](LICENSE.txt)