Updated endpoints to get 'trip' and 'item' to work together without using explode()
Remove debugging wp_send_json
Updated JS app starting file to accept new 'line_item_id' parameter
Updated get_order_by_line_item_id to no longer require an order_id
Removed uneccesary query_var check before including the edit trip .php file
Merge branch 'owen' of https://github.com/sagalbot/epicrides-core into owen