[TIMOB-1658] iOS: Ti.File.write always returns false for binary data

var appDirName = Titanium.Filesystem.applicationDataDirectory;
var txtFile = Titanium.Filesystem.getFile(appDirName, 'foobar.txt');
var binFile = Titanium.Filesystem.getFile(appDirName, 'foobar.bin');

var text = "Sudo make me a sandwich.";

if (!txtFile.exists()) {
    Titanium.API.debug("File " + txtFile.name + " does not exist yet.");
}

if (!binFile.exists()) {
    Titanium.API.debug("File " + binFile.name + " does not exist yet.");
}

if (txtFile.write(text)) {
    Titanium.API.debug("I successfully wrote text to the file.");
} else {
    Titanium.API.debug("I was not able to write text to the file. Oh no!");
}

var blob = Titanium.Utils.base64decode(text); // make some bin data

if (binFile.write(blob)) {
    Titanium.API.debug("I successfully wrote a blob to the file.");
} else {
    Titanium.API.debug("I was not able to write a blob to the file. Oh no!");
}

// Do they exist now?
if (txtFile.exists()) {
    Titanium.API.debug(txtFile.name + " exists, contents: " + txtFile.read());
}

if (binFile.exists()) {
    // Note: Titanium.Filesystem.File.size attribute not mentioned in the API docs
    Titanium.API.debug(binFile.name + " exists, size: " + binFile.size);
}