(#798) Add PinPackage element to packages.config

This adds the PinPackages element to the deffinition of the
packages.config format. This allows the pin-packages argument
to be used via a config file.

Author: TheCakeIsNaOH

src/chocolatey/infrastructure.app/configuration/PackagesConfigFilePackageSetting.cs

@@ -158,5 +158,8 @@ public sealed class PackagesConfigFilePackageSetting
 
         [XmlAttribute(AttributeName = "noProgress")]
         public bool NoProgress { get; set; }
+
+        [XmlAttribute(AttributeName = "pinPackage")]
+        public bool PinPackage { get; set; }
     }
 }

src/chocolatey/infrastructure.app/services/ChocolateyPackageService.cs

@@ -778,6 +778,7 @@ private IEnumerable<ChocolateyConfiguration> get_packages_from_config(string pac
                     if (pkgSettings.FailOnStderr) packageConfig.Features.FailOnStandardError = true;
                     if (pkgSettings.UseSystemPowershell) packageConfig.Features.UsePowerShellHost = false;
                     if (pkgSettings.NoProgress) packageConfig.Features.ShowDownloadProgress = false;
+                    if (pkgSettings.PinPackage) packageConfig.PinPackage = true;
 
                     this.Log().Info(ChocolateyLoggers.Important, @"{0}".format_with(packageConfig.PackageNames));
                     packageConfigs.Add(packageConfig);