Allow batch downloads to use same nice file format as GUI

As we often use batch downloads and sometimes the GUI, it's good to have the filenames consistent. Also, having the title in the filename makes it easier to know which kids shows we have watched compared to numbers.

This patch brings the same filename format as the GUI to the batch downloader (hadn't seen all of https://github.com/vadmium/python-iview/pull/6 until after I did this code, so it may solve that issue)