Add spec file for Chocolatey

fixes #8503

icinga2.nuspec

@@ -0,0 +1,26 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Do not remove this test for UTF-8: if ??? doesn?t appear as greek uppercase omega letter enclosed in quotation marks, you should use an editor that supports UTF-8, not this one. -->
+<!--package xmlns="http://schemas.microsoft.com/packaging/2010/07/nuspec.xsd"-->
+<package xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
+  <metadata>
+    <!-- Read this before publishing packages to chocolatey.org: https://github.com/chocolatey/chocolatey/wiki/CreatePackages -->
+    <id>icinga2</id>
+    <title>Icinga2</title>
+    <version>2.3.5</version>
+    <authors>2015 - The Icinga Project</authors>
+    <owners>Martin Schuster</owners>
+    <summary>icinga2 - Monitoring Agent for Windows</summary>
+    <description>Icinga2, make the way for the next generation </description>
+    <projectUrl>http://www.icinga.org</projectUrl>
+    <tags>icinga2 agent monitoring</tags>
+    <licenseUrl>http://www.icinga.org/icinga/faq</licenseUrl>
+    <requireLicenseAcceptance>false</requireLicenseAcceptance>
+    <iconUrl>https://www.icinga.org/wp-content/uploads/2015/05/icinga_icon_128x128.png</iconUrl>
+    <dependencies>
+      <dependency id="DotNet3.5" />
+    </dependencies>
+  </metadata>
+  <files>
+    <file src="tools\**" target="tools" />
+  </files>
+</package>

tools/chocolateyInstall.ps1

@@ -0,0 +1,7 @@
+$packageName = 'icinga2'
+$installerType = 'exe'
+$url = 'http://packages.icinga.org/windows/Icinga2-v2.3.5.exe'
+$silentArgs = '/S'
+$validExitCodes = @(0)
+
+Install-ChocolateyPackage "$packageName" "$installerType" "$silentArgs" "$url" -validExitCodes $validExitCodes