Adding loadersettings free FileManager impl

Starting to remove the giant cyclic dependency that is the `LoaderSettings` from the [BasicFileManager](https://github.com/novoda/ImageLoader/blob/develop/core/src/main/java/com/novoda/imageloader/core/file/BasicFileManager.java)

- The impl also removes the internal thread handling for deleting files from the cache, it should be done from the client rather than hidden.