Revision BraftonImage.php

Implemented uploads_Directory_Exists method. was originally 
not in use. Added it to the dowload_Brafton_Image method.

Cleaned up the public method. 

Added class usage example. Argument key names are important and cannot be changed. We should agree on this

if blocks use yoda statements as recommended by wordpress vip. 

Not sure if public method should return anything. Perhaps attachment_Id? TO discuss