Fix extension load issue with spaces in usernames

This change fixes #244 which reports that the extension does not load when
the user's username contains a space.  This was caused by the script
execution of Start-EditorServices.ps1 not being contained within quotes.

Author: daviwil

src/main.ts

@@ -177,7 +177,7 @@ function startPowerShell(powerShellExePath: string, bundledModulesPath: string,
 
         // Add the Start-EditorServices.ps1 invocation arguments
         args.push('-Command')
-        args.push(startScriptPath + ' ' + startArgs)
+        args.push('& "' + startScriptPath + '" ' + startArgs)
 
         // Launch PowerShell as child process
         powerShellProcess = cp.spawn(powerShellExePath, args);