Added PyPi badge

Author: Mark Gibbs

README.md

@@ -1,5 +1,6 @@
 # django-plotly-dash
 
+[![PyPI version](https://badge.fury.io/py/django-plotly-dash.svg)](https://badge.fury.io/py/django-plotly-dash)
 ![Develop Branch Build Status](https://travis-ci.org/GibbsConsulting/django-plotly-dash.svg?branch=master)
 
 Expose [plotly dash](https://plot.ly/products/dash/) apps as [Django](https://www.djangoproject.com/) tags. Multiple Dash apps can