Error on 'mkdir' under Windows 

Under Windows 10, when running `gravitate new`, everything is fine until the generation of the grav project : 

```
return binding.mkdir(pathModule._makeLong(path),
                 ^

Error: ENOENT: no such file or directory, mkdir 'C:\Users\T__\WebProjects\temp\gravitate-grav-master\user\themes\<%= siteSlug %>'
```