National variants

[jiri-janousek]

Hi. I'm not going to merge this pull request as it's an example how a pull request should not look like. I know it's partially my fault as there are no guidelines for pull requests. I hope to fix this next month though. Please read a draft of Contributing Guidelines at tiliado/nuvolaplayer#128 and create a new well formed pull request. It must be so good that I'm able to merge it in the evening pretty tired after work. And without beating a desk with my head.

1. Vague summary for commits

   • 742c542 "Update metada.json" -> I have no idea what did you exactly updated and why without looking at the code. Maybe "Remove extra comma in metadata causing JSON error"?
   • ee61679 "Update metadata.json" -> Again, no idea why you have done this.

   • ca4072d "national variants" -> This commit deserve more love:

     Add support of national variants (com, de, fr, co.uk)
     
     Amazon Cloud Player has multiple national variants with
     different URL. Initialization form is used to let user
     select its preferred national variant for the first time
     and this option can be later changed in Preferences
     form.

   • You should squash the tree commits into a single commit "Add support of national variants (com, de, fr, co.uk)...". If are not sure how to do it, let me know.

2. Pull request with insufficient title (summary) and no description:

   • Title: Add support of national variants (de, fr, co.uk)
   • Description (use a text editor with mark at 72 characters to check wrapping):

   Amazon Cloud Player has multiple national variants with
   different URL. Initialization form is used to let user
   select its preferred national variant for the first time
   and this option can be later changed in Preferences
   form.
   
   Author: Your Name <your@email>
   Reviewed by: FIXME <FIXME>

Please don't take my criticism personally, but I need to start to push a bit of quality to the project.