Adjust volume of audio files to a standard level

Current version

normalize requires the following formula to be installed:
mad 0.15.1b MPEG audio decoder

Formula history

Mike McQuaid Use hash rockets again. (#5177)
Mike McQuaid Use Ruby 1.9+ symbol hash keys in all formulae. (#4942)
Viktor Szakats normalize: use secure url (redirected to cleartext)
Viktor Szakats normalize: follow url redirect
Dominyk Tiller normalize: fix test
Nikolaus Wittenstein Add descriptions to all remaining homebrew packages
Ted Pennings Convert all 'def test' formulae to 'test do'
Adam Vandenberg normalize/num-utils conflict
Jack Nagel normalize: use recommended dep