U4-4930 NuGet update fails to copy new Umbraco binaries

build/NuSpecs/UmbracoCms.Core.nuspec

@@ -67,5 +67,6 @@
         <file src="..\_BuildOutput\WebApp\bin\umbraco.XmlSerializers.dll" target="lib\umbraco.XmlSerializers.dll" />
         <file src="..\_BuildOutput\WebApp\bin\UmbracoExamine.dll" target="lib\UmbracoExamine.dll" />
         <file src="..\_BuildOutput\WebApp\bin\UrlRewritingNet.UrlRewriter.dll" target="lib\UrlRewritingNet.UrlRewriter.dll" />
+		<file src="tools\install.core.ps1" target="tools\install.ps1" />
     </files>
 </package>

build/NuSpecs/tools/install.core.ps1

@@ -0,0 +1,24 @@
+param($rootPath, $toolsPath, $package, $project)
+
+if ($project) {
+	$dateTime = Get-Date -Format yyyyMMdd-HHmmss
+	$backupPath = Join-Path (Split-Path $project.FullName -Parent) "\App_Data\NuGetBackup\$dateTime"
+	$copyLogsPath = Join-Path $backupPath "CopyLogs"
+	$projectDestinationPath = Split-Path $project.FullName -Parent
+	
+	# Create backup folder and logs folder if it doesn't exist yet
+	New-Item -ItemType Directory -Force -Path $backupPath
+	New-Item -ItemType Directory -Force -Path $copyLogsPath
+	
+	# After backing up, remove all dlls from bin folder in case dll files are included in the VS project
+	# See: http://issues.umbraco.org/issue/U4-4930
+	$umbracoBinFolder = Join-Path $projectDestinationPath "bin"
+	if(Test-Path $umbracoBinFolder) {
+		$umbracoBinBackupPath = Join-Path $backupPath "bin"
+		
+		New-Item -ItemType Directory -Force -Path $umbracoBinBackupPath
+		
+		robocopy $umbracoBinFolder $umbracoBinBackupPath /e /LOG:$copyLogsPath\UmbracoBinBackup.log
+		Remove-Item $umbracoBinFolder\*.dll -Force -Confirm:$false
+	}
+}