try to fix powershell variable expansion

appveyor.yml

@@ -4,32 +4,6 @@ environment:
   node_pre_gyp_secretAccessKey:
     secure: 1amwJJw9fu0j6dXnc5KsAQbSYf7Cjw/dapT6OZWABa6nc52grkKeLQ+DGaOfQz8i
   matrix:
-    - nodejs_version: 0.10.32
-      nw_version: 0.8.6
-      platform: x86
-      msvs_toolset: 12
-    - nodejs_version: 0.10.32
-      nw_version: 0.8.6
-      platform: x64
-      msvs_toolset: 12
-    - nodejs_version: 0.11.13
-      nw_version: 0.10.5
-      platform: x86
-      msvs_toolset: 12
-    - nodejs_version: 0.11.13
-      nw_version: 0.10.5
-      platform: x64
-      msvs_toolset: 12
-    - nodejs_version: 0.11.13
-      nw_version: 0.10.5
-      platform: x86
-      msvs_toolset: 12
-      BUILD_ARGS: --target=0.11.14
-    - nodejs_version: 0.11.13
-      nw_version: 0.10.5
-      platform: x64
-      msvs_toolset: 12
-      BUILD_ARGS: --target=0.11.14
     # custom visual studio 2014 builds
     - nodejs_version: 0.10.33
       platform: x64
@@ -61,8 +35,8 @@ install:
   - if %platform% == x64 (SET ARCHPATH="x64/")
   # install node version per visual studio toolset
   - if "%msvs_toolset%" == "12" powershell Install-Product node $env:nodejs_version $env:platform
-  - if "%msvs_toolset%" == "14" powershell Write-Output "fetching https://mapbox.s3.amazonaws.com/node-cpp11/v$env:nodejs_version/$env:ARCHPATHnode.exe"
-  - if "%msvs_toolset%" == "14" powershell Start-FileDownload "https://mapbox.s3.amazonaws.com/node-cpp11/v$env:nodejs_version/$env:ARCHPATHnode.exe"
+  - if "%msvs_toolset%" == "14" powershell Write-Output "fetching https://mapbox.s3.amazonaws.com/node-cpp11/v$env:nodejs_version/${env:ARCHPATH}node.exe"
+  - if "%msvs_toolset%" == "14" powershell Start-FileDownload "https://mapbox.s3.amazonaws.com/node-cpp11/v$env:nodejs_version/${env:ARCHPATH}node.exe"
   # only needed if not using 'os: Visual Studio 2014 CTP4'
   #- if "%msvs_toolset%" == "14" powershell Write-Output "https://mapbox.s3.amazonaws.com/node-cpp11/vcredist_$env:platform.exe"
   #- if "%msvs_toolset%" == "14" powershell Start-FileDownload "https://mapbox.s3.amazonaws.com/node-cpp11/vcredist_$env:platform.exe"