Update appveyor config.

Author: viceice

appveyor.yml

@@ -1,16 +1,28 @@
 version: 1.0.0-{build}
-image: Visual Studio 2017
 pull_requests:
   do_not_increment_build_number: true
 branches:
   only:
   - master
+skip_tags: true
+max_jobs: 1
+clone_depth: 1
+
+image: Visual Studio 2017
+
 cache:
   - '%USERPROFILE%\.nuget\packages -> **\*.csproj'
 
 init:
   - git config --global core.autocrlf true
 
+nuget:
+  account_feed: true
+  project_feed: true
+  disable_publish_on_pr: true
+
+configuration: Release
+
 before_build:
   - dotnet --version
   - dotnet restore --verbosity m
@@ -24,6 +36,3 @@ test:
   assemblies:
     only:
       - 'UnitTests\bin\**\UnitTests.dll'
-
-# artifacts:
-#   - path: '**\*.nupkg'