Update paypal.php

Parameter "notify_url" added to make PayPal IPN work without having to set it manually in the PayPal account.
Added support for WPML

Signed-off-by: Zane M. Kolnik <zanematthew@gmail.com>
Merge branch 'master' of github.com:NETLINK/sell-media into NETLINK-dev
Adding fix for when original image is purchased download link is not available in some shortcodes
updating readme
Width was duplicated, where height should of been
Plugin options ported over, fully working
Rename gpp to sell_media
Moving options to settings
Added basic tabs
Added price groups, organized functions
Removing unused files and options, added plugin data to settings header
removing unused file
Adding filter for payment gateways
Fixing admin notices
Removing old settings, merging array for old new optionsclear
Removed admin settings
no need for this global
removing 'none' in place of 'null'
Start of update script