Modifying the image processor to optionally add imported images to the database

A proposed solution to #114. Note that this does not yet allow the user to specify an alternate media db, it just uses the db that Magmi is configured to use. Since it uses the target file, it should work with remote images as well as local images.
Put this code before the chmod , even before any file operations (with $this->_mdh) , so i'll place this just right after line 508.
I would also isolate it in a separate method (insertImageInDB)