message: Add code coverage badge
diff: -[![CircleCI](https://img.shields.io/circleci/build/github/xpring-eng/Xpring-JS/master?style=flat-square&token=8f614950de4d2dc800bb51710667bbd90d82dda3)](https://circleci.com/gh/xpring-eng/Xpring-JS)
  -
  +[![CircleCI](https://img.shields.io/circleci/build/github/xpring-eng/Xpring-JS/master?style=flat&token=8f614950de4d2dc800bb51710667bbd90d82dda3)](https://circleci.com/gh/xpring-eng/Xpring-JS)
  +[![Coverage](https://coveralls.io/repos/github/xpring-eng/Xpring-JS/badge.svg?t=DkDKCV)](https://coveralls.io/github/xpring-eng/Xpring-JS)
  # XRP-JS
  XRP JS provides a Javascript based SDK for interacting with the Ripple Ledger.
  