Methods that deal with PersistentDictionary{TKey,TValue} database files.
        /// <summary>
        /// Determine if a dictionary database file exists in the specified directory.
        /// </summary>
        /// <param name="directory">The directory to look in.</param>
        /// <returns>True if the database file exists, false otherwise.</returns>
        public static bool Exists(string directory)
        {
            if (null == directory)
            {
                throw new ArgumentNullException("directory");
            }

            if (Directory.Exists(directory))
            {
                var defaultConfig = PersistentDictionaryDefaultConfig.GetDefaultDatabaseConfig();
                var config        = new DatabaseConfig()
                {
                    DatabaseFilename = Path.Combine(directory, defaultConfig.DatabaseFilename)
                };
                config.Merge(defaultConfig, MergeRules.KeepExisting);
                return(PersistentDictionaryFile.Exists(config));
            }

            return(false);
        }
        // File/Directory not availble in Windows Store Apps.
#else
        /// <summary>
        /// Delete all files associated with a PersistedDictionary database from
        /// the specified directory.
        /// </summary>
        /// <param name="directory">The directory to delete the files from.</param>
        public static void DeleteFiles(string directory)
        {
            if (null == directory)
            {
                throw new ArgumentNullException("directory");
            }

            if (Directory.Exists(directory))
            {
                var defaultConfig = PersistentDictionaryDefaultConfig.GetDefaultDatabaseConfig();
                var config        = new DatabaseConfig()
                {
                    DatabaseFilename = Path.Combine(directory, defaultConfig.DatabaseFilename),
                    SystemPath       = directory,
                    LogFilePath      = directory,
                    TempPath         = directory,
                };
                config.Merge(defaultConfig, MergeRules.KeepExisting);
                PersistentDictionaryFile.DeleteFiles(config);
            }
        }