Use the system-available quarantine string to get the quarantine metadata attribute.
Use some 10.10-specific APIs to remove the quarantine attribute.
Indenting code.
Better, forward-compatible way of looking up NSURLQuarantinePropertiesKey, as suggested by @jakepetroules
Minor fix.
Don't use new code if specifically targeting OS versions that have the new API.
remove unnecessary return;
Merge pull request #387 from MaddTheSane/QuarantineVal

Quarantine removal