Override default NSFileProtection handling

Added a new constructor to override default NSFileProtection level
choosing.
Useful if you are a jailbreak dev.
renamed _forcedFileProtectionLevel to ...

… _defaultFileProtectionLevel and fixed indentation.
Indention #2
Indetation #3
comment corrected
Fix Travis build
Merge pull request #285 from beatjunky99/master

Override default NSFileProtection handling