resolves #289 #291 attributes as string or array

- includes tests for properly splitting on spaces
resolves #290 safe mode set using string, symbol or int

- this change makes safe mode resolution a lot more robust
Merge pull request #293 from mojavelinux/safe-level-as-str

resolves #290 safe mode set using string, symbol or int
Merge pull request #292 from mojavelinux/attributes-as-str-or-arr

resolves #289 #291 attributes as string or array
resolves #301 handle author(s) defined using attributes