NSData: Implement +dataWithContentsOfXXX:options:error: and -initdataWithContentsOfXXX:options:error:

[buzzdeee]

+ dataWithContentsOfFile:options:error: Creates a data object by reading every byte from the file at a given path. + dataWithContentsOfURL:options:error: Creates a data object from the data at the provided file URL using specific reading options.

- initWithContentsOfFile:options:error: Initializes a data object with the content of the file at a given path.

- initWithContentsOfURL:options:error: Creates a data object from the data at the provided file URL using specific reading options.