feat(preprocessor): add 'mp3' and 'ogg' as binary formats to avoid media corruption in the browser.
fix(travis_ci): converted node versions as string

It avoids the `0.1` version number in Travis builds.

Cf. http://docs.travis-ci.com/user/languages/javascript-with-nodejs/#Choosing-Node-versions-to-test-against
Merge pull request #1104 from oncletom/patch-2

chore(travis_ci): converted node versions as string
Merge pull request #1103 from oncletom/patch-1

feat(preprocessor): add 'mp3' and 'ogg' as binary formats
resolve merge conflicts