Fix appveyor config.

Author: ivanz

appveyor.yml

@@ -1,33 +1,14 @@
 environment:
   nuget_version: '2.6.0-beta1'
   assembly_version: '2.6.0'
+  nuget_prerelease: true
 
 version: '$(nuget_version)+{build}'
 
-deploy:
-  - provider: GitHub
-    description: |
-      * Fix to support for VS 2017 15.5.x
-
-    on:
-      appveyor_repo_tag: true
-    prerelease: $(nuget_prerelease)
-
-    release: v$(nuget_version)
-    auth_token:
-      secure: VrF5TrpBRN0ims9nJC1LG32O6ga5hsRuGNSufEbatAiIWZ1z68iiCYKZtqnAaT9y
-
-  - provider: NuGet
-    api_key:
-      secure: R+qirYPrTX9IzJHpRLL6KAV1Lo+vlAnInf6ShiIB2rAGIP28ceJxRAh1jirHE/uD
-    on:
-      appveyor_repo_tag: true
-
 pull_requests:
   do_not_increment_build_number: true
 
 configuration: Release
-
 image: Visual Studio 2017
 
 dotnet_csproj:
@@ -36,13 +17,30 @@ dotnet_csproj:
   version: '$(nuget_version)'
   assembly_version: '$(assembly_version)'
 
+before_build: dotnet restore
+
 build:
   publish_nuget: true
   publish_nuget_symbols: true
   verbosity: minimal  
 
 test_script: dotnet test -c %CONFIGURATION% Source\Machine.VSTestAdapter.Specs
 
-artifacts:
-- path: Source\**\*.nupkg
+deploy:
+  - provider: GitHub
+    description: |
+      * Fix to support for VS 2017 15.5.x
+
+    on:
+      appveyor_repo_tag: true
+    prerelease: $(nuget_prerelease)
+
+    release: v$(nuget_version)
+    auth_token:
+      secure: VrF5TrpBRN0ims9nJC1LG32O6ga5hsRuGNSufEbatAiIWZ1z68iiCYKZtqnAaT9y
 
+  - provider: NuGet
+    api_key:
+      secure: R+qirYPrTX9IzJHpRLL6KAV1Lo+vlAnInf6ShiIB2rAGIP28ceJxRAh1jirHE/uD
+    on:
+      appveyor_repo_tag: true