Add AppVeyor file

Author: geoperez

appveyor.yml

@@ -0,0 +1,20 @@
+version: '1.0.{build}'
+configuration:
+- Debug
+- Release
+platform: Any CPU
+environment:
+  # Don't report back to the mothership
+  DOTNET_CLI_TELEMETRY_OPTOUT: 1
+init:
+- ps: $Env:LABEL = "CI" + $Env:APPVEYOR_BUILD_NUMBER.PadLeft(5, "0")
+before_build:
+- appveyor-retry dotnet restore -v Minimal
+build_script:
+- dotnet build "src\Unosquare.Labs.LiteLib" -c %CONFIGURATION% --no-dependencies --version-suffix %LABEL%
+test_script:
+- dotnet test "test\Unosquare.Labs.LiteLib.Tests" -c %CONFIGURATION%
+artifacts:
+- path: artifacts\**\*.*
+cache:
+- '%USERPROFILE%\.nuget\packages'