Add badges for CI build status

Author: tschuchortdev

README.md

@@ -7,6 +7,8 @@
 ![GitHub](https://img.shields.io/github/license/tschuchortdev/kotlin-compile-testing.svg?color=green&style=popout)
 ![Maintenance](https://img.shields.io/maintenance/yes/2019.svg?style=popout)
 [![Generic badge](https://img.shields.io/badge/contributions-welcome-green.svg)](https://shields.io/)
+[![Build Status](https://travis-ci.com/tschuchortdev/kotlin-compile-testing.svg?branch=master)](https://travis-ci.com/tschuchortdev/kotlin-compile-testing)
+[![Build status](https://ci.appveyor.com/api/projects/status/jj639rc6whehaf9o?svg=true)](https://ci.appveyor.com/project/tschuchortdev/kotlin-compile-testing)
 
 A library for in-process compilation of Kotlin and Java code, in the spirit of [Google Compile Testing](https://github.com/google/compile-testing). For example, you can use this library to test your annotation processors or run Kotlin-script files.