Add support for secure file options
Add support for secure file options

- Create new interface, ISecureFileOptions
- Add "secure" key to IFileOptions interface.
dsebastien/DefinitelyTyped,georgemarshall/DefinitelyTyped,georgemarshall/DefinitelyTyped,markogresak/DefinitelyTyped,georgemarshall/DefinitelyTyped,borisyankov/DefinitelyTyped,georgemarshall/DefinitelyTyped,borisyankov/DefinitelyTyped,dsebastien/DefinitelyTyped,mcliment/DefinitelyTyped