[BUG] Missing trailing slash for image file in Windows installer

[narotic]

I noticed that there seems to be a missing trailing slash in the path used to download or read images in the Windows installer. For instance, running "XBian-installer.exe" from "E:\software\xbian", the image is downloaded to "E:\software\xbianXBian_1.0_Beta_2.img.gz" instead of "E:\software\xbian\XBian_1.0_Beta_2.img.gz".

This of course makes it inconvenient to use pre-downloaded images. Fixing this should be trivial and makes it also easier to see where the images are actually downloaded (I found a couple of threads asking this).