add logic to build blenderbim-nightly chocolatey package

choco/blenderbim/tools/chocolateybeforemodify.ps1

@@ -0,0 +1,11 @@
+$processName      = "blender"
+$blenderIsRunning = Get-Process -Name $processName -ErrorAction SilentlyContinue
+
+if($blenderIsRunning -eq $null) {
+    echo "Blender is not running ready for next action."
+}
+else {
+    Write-Warning "$processName is still running - installer cannot safely proceed to next action."
+    Write-Warning "Please retry after closing all running blender applications."
+    exit 1
+}