Add a retry for SplunkForwarder stoppage

Attempt at fixing https://github.com/clong/DetectionLab/issues/243

Vagrant/scripts/install-inputsconf.ps1

@@ -9,7 +9,13 @@ $targetContent = get-content c:\vagrant\resources\splunk_forwarder\inputs.conf
 if ($currentContent -ne $targetContent)
 {
   Write-Host "Stopping the Splunk forwarder"
-    Stop-Service splunkforwarder
+  try {
+    Stop-Service splunkforwarder -ErrorAction Stop
+  } catch {
+    Write-Host "Failed to stop SplunkForwarder. Trying again..."
+    Set-Location "C:\Program Files\SplunkUniversalForwarder\bin"
+    & ".\splunk.exe" "stop"
+  }
 
   Write-Host "Deleting the default configuration"
   Remove-Item $inputsPath