ID3 tags and other small improvements

I just saw that there was another ID3 tag pull request. damn.

But I made two other minor changes in there which might be good. 
1. I just moved the fetching code below the file check, so that if you already have the file, it wont re-download it. Speeds up the script a little bit.

2. It asks user input for the area to scrape and number of pages so you don't have to go into the file to change  parameters. Just pressing enter when it asks passes in default parameters.

3. And yes, it adds simple artist and title ID3 tags using mutagen.