Add comprehensive test suite, fix minor issues, rename function and file names to match approved verbs (#708)

Scripts/Helpers/Get-UserName.ps1

@@ -0,0 +1,11 @@
+<#
+    .SYNOPSIS
+        Returns the explicitly targeted user name or the current process user name.
+#>
+function Get-UserName {
+    if ($script:Params.ContainsKey("User")) {
+        return $script:Params.Item("User")
+    }
+
+    return $env:USERNAME
+}