Asynchronously list subdirectories in a directory.

Example

var FileSystem = require("FuseJS/FileSystem");

FileSystem.listDirectories(FileSystem.dataDirectory)
    .then(function(directories) {
        console.log("There are " + directories.length + " subdirectories in directory")
    }, function(error) {
        console.log("Unable to list subdirectories of directory: " + error);
    });