Add support for Decibel

[matjolic]

Would be very much appreciated :)
http://sbooth.org/Decibel/

[hoke-t]

Implemented here: https://github.com/hoke-t/BackgroundMusic/tree/Decibel

Will submit pull request once #27 is accepted (or denied)

[kyleneideck]

Thanks, @hoke-t. I haven't tested https://github.com/hoke-t/BackgroundMusic/tree/Decibel yet, but I just read through it and it looks good to me. Just two minor things:

• When you moved the new files to BGMApp/BGMApp/Music Players you forgot to git rm the copies in BGMApp/BGMApp.
• Would it be better to link to https://sbooth.org/Decibel/ instead of http://sbooth.org/Decibel/ in the README? (If so, we should do the same for the link to VOX.)

[DotTheI]

Second this request

[hoke-t]

Working on it now.

[hoke-t]

Sorry the PR failed check, will fix it when I get a chance and resubmit.