Update appveyor.yml: Do not publish artifacts except on master.

appveyor.yml

@@ -6,6 +6,10 @@ image: Visual Studio 2017
 install:
 - git submodule update --init --recursive
 - ps: .\BuildTools\appveyor-install.ps1
+nuget:
+  account_feed: false
+  project_feed: true
+  disable_publish_on_pr: true
 before_build:
 - nuget restore ILSpy.sln
 build_script:
@@ -19,11 +23,16 @@ test:
 after_test:
 - python BuildTools\tidy.py
 for:
+- branches:
+    except:
+      - master
+  artifacts:
+    #nothing
 - branches:
     only:
       - master
-artifacts:
-  - path: ILSpy_binaries.zip
-    name: ILSpy %APPVEYOR_REPO_BRANCH% %ILSPY_VERSION_NUMBER% binaries
-  - path: '**\*.nupkg'
-    name: ICSharpCode.Decompiler %APPVEYOR_REPO_BRANCH% %ILSPY_VERSION_NUMBER% NuGet  
+  artifacts:
+    - path: ILSpy_binaries.zip
+      name: ILSpy %APPVEYOR_REPO_BRANCH% %ILSPY_VERSION_NUMBER% binaries
+    - path: '**\*.nupkg'
+      name: ICSharpCode.Decompiler %APPVEYOR_REPO_BRANCH% %ILSPY_VERSION_NUMBER% NuGet