Add AppVeyor support.

Author: XhmikosR

.appveyor.yml

@@ -0,0 +1,29 @@
+image:
+  - Visual Studio 2017
+
+version: "{build}"
+
+clone_depth: 5
+
+install:
+  - git submodule update --init --recursive
+  - set NASM_VER=2.13.03
+  - set NASM_FNAME_FULL=nasm-%NASM_VER%-win64
+  - set NASM_FNAME=nasm-%NASM_VER%
+  - set NASM_URL=https://www.nasm.us/pub/nasm/releasebuilds/%NASM_VER%/win64/%NASM_FNAME_FULL%.zip
+  - appveyor DownloadFile "%NASM_URL%"
+  - 7z x "%NASM_FNAME_FULL%.zip">NUL
+  - set "PATH=%CD%\%NASM_FNAME%;%PATH%"
+  - nasm -v
+
+build: off
+
+test_script:
+  - call "_build.bat"
+
+artifacts:
+  - path: Release\x64\jpegoptim.exe
+    name: jpegoptim
+
+matrix:
+  fast_finish: true

README.md

@@ -1,5 +1,7 @@
 # jpegoptim for Windows
 
+[![Build status](https://img.shields.io/appveyor/ci/XhmikosR/jpegoptim-windows/master.svg)](https://ci.appveyor.com/project/XhmikosR/jpegoptim-windows/branch/master)
+
 This is just my own project files for easy building of [jpegoptim](https://github.com/tjko/jpegoptim) with [mozjpeg](https://github.com/mozilla/mozjpeg) and Microsoft Visual Studio.
 Currently only 64-bit (x64) is targeted.