updated readme

README.md

@@ -3,7 +3,7 @@ Docstring coverage:
 ![docstring coverage](./badges/docstring_coverage.svg)
 Test coverage: 
 ![test coverage](./badges/test_coverage.svg)
-
+ [![astropy](http://img.shields.io/badge/powered%20by-AstroPy-orange.svg?style=flat)](http://www.astropy.org/) 
 Binary population synthesis code that interfaces with binary_c. Based on a original work by Jeff Andrews. Updated and extended for Python3 by David Hendriks, Robert Izzard.
 
 The current release is version [version](VERSION), make sure to use that version number when installing!