Merge pull request #12 from python-tableformatter/appveyor_badge

Added AppVeyor badge to README

Author: tleonhardt

README.md

@@ -2,6 +2,7 @@ tableformatter: tabular data formatter
 ======================================
 [![Latest Version](https://img.shields.io/pypi/v/tableformatter.svg?style=flat-square&label=latest%20stable%20version)](https://pypi.org/project/tableformatter/)
 [![Build status](https://api.travis-ci.com/python-tableformatter/tableformatter.svg?branch=master)](https://travis-ci.com/python-tableformatter/tableformatter)
+[![Appveyor build status](https://img.shields.io/appveyor/ci/anselor/tableformatter.svg?style=flat-square&label=windows%20build)](https://ci.appveyor.com/project/anselor/tableformatter)
 [![codecov](https://codecov.io/gh/python-tableformatter/tableformatter/branch/master/graph/badge.svg)](https://codecov.io/gh/python-tableformatter/tableformatter)
 
 tableformatter is a tabular data formatter allowing printing from both arbitrary tuples of strings or object inspection.