code: function getAvailableMigrations(vaultName, cb) {
  	var path = configuration.getMigrationsPath(vaultName);
  
  	fs.readdir(path, function (error, files) {
  		if (error) {
  			if (error.code === 'ENOENT') {
  				logger.warning('No migration folder found for vault', vaultName, '(skipping).');
  				return cb(null, []);
  			}
  
  			return cb(error);
  		}
  
  		var result = [];
  		for (var i = 0; i < files.length; i++) {
  			var file = files[i];
  			var ext = extname(file);
  
  			if (mage.isCodeFileExtension(ext)) {
  				result.push(basename(file, ext));
  			}
  		}
  
  		cb(null, result);
  	});
  }
docs: Scans the hard disk for available migration files for this vault and returns the version names.
  
  @param {string} vaultName  The vault name for which to migrate.
  @param {Function} cb       Callback that receives the found version numbers that can be migrated to or from.