Merge pull request #4760 from libgit2/ethomson/ci

ci: remove appveyor

README.md

@@ -2,7 +2,6 @@ libgit2 - the Git linkable library
 ==================================
 
 [![Travis Build Status](https://secure.travis-ci.org/libgit2/libgit2.svg?branch=master)](http://travis-ci.org/libgit2/libgit2)
-[![AppVeyor Build Status](https://ci.appveyor.com/api/projects/status/xvof5b4t5480a2q3/branch/master?svg=true)](https://ci.appveyor.com/project/libgit2/libgit2/branch/master)
 [![VSTS Build Status](https://libgit2.visualstudio.com/libgit2/_apis/build/status/libgit2)](https://libgit2.visualstudio.com/libgit2/_build/latest?definitionId=7)
 [![Coverity Scan Build Status](https://scan.coverity.com/projects/639/badge.svg)](https://scan.coverity.com/projects/639)
 

appveyor.yml

-version: '{build}'
-branches:
-  only:
-  - master
-  - appveyor
-  - /^maint.*/
-environment:
-  GITTEST_INVASIVE_FS_STRUCTURE: 1
-  GITTEST_INVASIVE_FS_SIZE: 1
-
-  matrix:
-  - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2013
-    CMAKE_OPTIONS: -G"Visual Studio 10 2010"
-    ARCH: x86
-  - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2013
-    CMAKE_OPTIONS: -G"Visual Studio 10 2010 Win64"
-    ARCH: amd64
-  - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
-    CMAKE_OPTIONS: -G"Visual Studio 14 2015"
-    ARCH: x86
-  - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
-    CMAKE_OPTIONS: -G"Visual Studio 14 2015 Win64"
-    ARCH: amd64
-  - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
-    CMAKE_OPTIONS: -G"MinGW Makefiles"
-    ARCH: x86
-  - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
-    CMAKE_OPTIONS: -G"MinGW Makefiles"
-    ARCH: amd64
-
-install:
-- set PATH=%TEMP%\mingw64\bin;%TEMP%\mingw32\bin;C:\ProgramData\Oracle\Java\javapath;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Program Files (x86)\CMake\bin
-- ps: |
-    mkdir build
-    cd build
-    if ($env:CMAKE_OPTIONS -eq '-G"MinGW Makefiles"') {
-      ../ci/setup-mingw.ps1
-    }
-
-build_script:
-- cmd: powershell ../ci/build.ps1
-
-test_script:
-- cmd: powershell ../ci/test.ps1