(GH-14) Adding IconUrl check

- To ensure that the IconUrl either comes from the same domain as the
ProjectUrl, or comes from the RawGit CDN
- Fixes GH-14

src/chocolatey.package.validator/chocolatey.package.validator.csproj

@@ -131,6 +131,7 @@
     <Compile Include="infrastructure.app\rules\CopyrightWordCountMinimum4Requirement.cs" />
     <Compile Include="infrastructure.app\rules\DocsUrlMissingSuggestion.cs" />
     <Compile Include="infrastructure.app\rules\IconUrlMissingGuideline.cs" />
+    <Compile Include="infrastructure.app\rules\IconUrlNotSameDomainAsProjectUrlDomainOrRawGitGuideline.cs" />
     <Compile Include="infrastructure.app\rules\InstallAutomationScriptNamedCorrectlyRequirement.cs" />
     <Compile Include="infrastructure.app\rules\LicenseUrlDoesNotMatchProjectUrlGuideline.cs" />
     <Compile Include="infrastructure.app\rules\LicenseUrlMissingGuideline.cs" />

src/chocolatey.package.validator/infrastructure.app/rules/IconUrlNotSameDomainAsProjectUrlDomainOrRawGitGuideline.cs

@@ -0,0 +1,40 @@
+// Copyright © 2015 - Present RealDimensions Software, LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+//
+// You may obtain a copy of the License at
+//
+// 	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+namespace chocolatey.package.validator.infrastructure.app.rules
+{
+    using NuGet;
+    using infrastructure.rules;
+
+    public class IconUrlNotSameDomainAsProjectUrlDomainOrRawGitGuideline : BasePackageRule
+    {
+        public override string ValidationFailureMessage { get { return "The package IconUrl should ideally come from the same domain name as the Project Url, or hosted on the RawGit CDN.  **NOTE:** For further information on how to setup your icon with a RawGit CDN URL, please visit this [article](https://github.com/chocolatey/choco/wiki/CreatePackages#package-icon-guidelines)."; } }
+
+        protected override PackageValidationOutput is_valid(IPackage package)
+        {
+            if(package.IconUrl == null) return true;
+
+            var iconUrlHost = package.IconUrl.Host;
+
+            // Since there is an iconUrl, but no Project Url, the check has to return false
+            // since the domains are definitely not the same
+            if(package.ProjectUrl == null) return false;
+
+            var projectUrlHost = package.ProjectUrl.Host;
+
+            return iconUrlHost == projectUrlHost || iconUrlHost == "cdn.rawgit.com";
+        }
+    }
+}