appveyor: add VS2017, config file formatting

appveyor.yml

@@ -4,29 +4,31 @@ branches:
   - master
   - book
 os: 
-- Visual Studio 2013
-- Visual Studio 2015
+  - Visual Studio 2013
+  - Visual Studio 2015
+  - Visual Studio 2017
 configuration: Release
 platform: x64
 clone_folder: c:\pbrt-v3
+
 install:
-# os detection
-- ps: if ($env:VS140COMNTOOLS -gt 0) { $env:VS_VER = 14 } else { $env:VS_VER = 12 }
-- echo %VS_VER%
-- set PATH=C:\Program Files (x86)\MSBuild\%VS_VER%.0\Bin;%PATH%
-- echo %PATH%
-- git submodule update --init --recursive
+  # os detection
+  - ps: if ($env:VS140COMNTOOLS -gt 0) { $env:VS_VER = 14 } else { $env:VS_VER = 12 }
+  - echo %VS_VER%
+  - set PATH=C:\Program Files (x86)\MSBuild\%VS_VER%.0\Bin;%PATH%
+  - echo %PATH%
+  - git submodule update --init --recursive
 before_build:
-- md c:\pbrt-v3\build
-- cd c:\pbrt-v3\build
-- set WIN32=1
-- ps: if ($env:VS_VER -eq 14) {cmake -G "Visual Studio 14 2015 Win64" ..} else {cmake -G "Visual Studio 12 2013 Win64" ..}
+  - md c:\pbrt-v3\build
+  - cd c:\pbrt-v3\build
+  - set WIN32=1
+  - ps: if ($env:VS_VER -eq 14) {cmake -G "Visual Studio 14 2015 Win64" ..} else {cmake -G "Visual Studio 12 2013 Win64" ..}
 build:
   project: c:\pbrt-v3\build\pbrt-v3.sln
   parallel: true
   verbosity: normal
 build_script:
-- msbuild c:\pbrt-v3\build\pbrt-v3.sln /logger:"C:\Program Files\AppVeyor\BuildAgent\Appveyor.MSBuildLogger.dll"
+  - msbuild c:\pbrt-v3\build\pbrt-v3.sln /logger:"C:\Program Files\AppVeyor\BuildAgent\Appveyor.MSBuildLogger.dll"
 after_build:
-- cd c:\pbrt-v3\build\Release
-- pbrt_test.exe
+  - cd c:\pbrt-v3\build\Release
+  - pbrt_test.exe