Make storage URL method public

LeStorage/Storable.swift

@@ -47,7 +47,7 @@ extension Storable {
         return path
     }
     
-    static func storageDirectoryPath() throws -> URL {
+    public static func storageDirectoryPath() throws -> URL {
         return try FileUtils.pathForDirectoryInDocuments(directory: Store.storageDirectory)
     }