chore: add ci badges

Author: zachdaniel

README.md

@@ -1,5 +1,11 @@
 # SpandexDatadog
 
+[![CircleCI](https://circleci.com/gh/spandex-project/spandex.svg?style=svg)](https://circleci.com/gh/spandex-project/spandex_datadog)
+[![Inline docs](http://inch-ci.org/github/spandex-project/spandex.svg)](http://inch-ci.org/github/spandex-project/spandex_datadog)
+[![Coverage Status](https://coveralls.io/repos/github/spandex-project/spandex/badge.svg)](https://coveralls.io/github/spandex-project/spandex_datadog)
+[![Hex pm](http://img.shields.io/hexpm/v/spandex.svg?style=flat)](https://hex.pm/packages/spandex_datadog)
+[![Ebert](https://ebertapp.io/github/spandex-project/spandex.svg)](https://ebertapp.io/github/spandex-project/spandex_datadog)
+
 A datadog adapter for the `spandex` library.
 
 ## Installation