chore(appveyor): adds appveyor logo

Author: mdreizin

README.md

@@ -1,6 +1,6 @@
 [![NPM version](http://img.shields.io/npm/v/webpack-config.svg)](https://www.npmjs.org/package/webpack-config)
 [![Travis build status](http://img.shields.io/travis/Fitbit/webpack-config/master.svg)](https://travis-ci.org/Fitbit/webpack-config)
-[![AppVeyor build status](https://img.shields.io/appveyor/ci/mdreizin/webpack-config/master.svg)](https://ci.appveyor.com/project/mdreizin/webpack-config/branch/master)
+[![AppVeyor build status](https://img.shields.io/appveyor/ci/mdreizin/webpack-config/master.svg?logo=data%3Aimage%2Fsvg%2Bxml%3Bbase64%2CPHN2ZyB3aWR0aD0iNDAiIGhlaWdodD0iNDAiIHZpZXdCb3g9IjAgMCA0MCA0MCIgeG1sbnM9Imh0dHA6Ly93d3cudzMub3JnLzIwMDAvc3ZnIj48cGF0aCBkPSJNMjAgMGMxMSAwIDIwIDkgMjAgMjBzLTkgMjAtMjAgMjBTMCAzMSAwIDIwIDkgMCAyMCAwem00LjkgMjMuOWMyLjItMi44IDEuOS02LjgtLjktOC45LTIuNy0yLjEtNi43LTEuNi05IDEuMi0yLjIgMi44LTEuOSA2LjguOSA4LjkgMi44IDIuMSA2LjggMS42IDktMS4yem0tMTAuNyAxM2MxLjIuNSAzLjggMSA1LjEgMUwyOCAyNS4zYzIuOC00LjIgMi4xLTkuOS0xLjgtMTMtMy41LTIuOC04LjQtMi43LTExLjkgMEwyLjIgMjEuNmMuMyAzLjIgMS4yIDQuOCAxLjIgNC45bDYuOS03LjVjLS41IDMuMy43IDYuNyAzLjUgOC44IDIuNCAxLjkgNS4zIDIuNCA4LjEgMS44bC03LjcgNy4zeiIgZmlsbD0iI0NDQyIgZmlsbC1ydWxlPSJub256ZXJvIi8%2BPC9zdmc%2B)](https://ci.appveyor.com/project/mdreizin/webpack-config/branch/master)
 [![Code Climate GPA](https://img.shields.io/codeclimate/github/Fitbit/webpack-config.svg)](https://codeclimate.com/github/Fitbit/webpack-config)
 [![Code Climate Coverage](https://img.shields.io/codeclimate/coverage/github/Fitbit/webpack-config.svg)](https://codeclimate.com/github/Fitbit/webpack-config)
 [![Dependency Status](https://img.shields.io/david/Fitbit/webpack-config.svg)](https://david-dm.org/Fitbit/webpack-config)