Replace to new PNG files (Font Awesome 4.0.3)

https://github.com/ruedap/fa2png
Update current-version.json
Update update.json
Update info.plist
Update README
Update CHANGELOG
Bump version to 4.0.3.0 (Font Awesome 4.0.3)
Workaround for failing build on Ruby 1.8.7

https://github.com/bundler/bundler/issues/2784
Merge pull request #52 from ruedap/improve-version-number

Bump version to 4.0.3.0 (Font Awesome 4.0.3)