Add initial EDD_DB class based off of the DB base class from AffiliateWP. #2256
First pass at the EDD_DB_Customers class. #2256
Add payment_ids column and remove unneeded defaults. #2256
Setup customers table to be created during install. #2256
Simplify add(). #2256
Rework existing EDD customers report table to use new customers DB. #2256
Add name column to DB. #2256
Rename cache group to just customers. #2256
Rework edd_get_purchase_stats_by_user() to use the new  customer API. #2256
Rework edd_count_total_customers() to use new customer API. #2256
Remove no-longer valid PHPDoc for edd_count_total_customers(). #2256
Update EDD_Customers_Export class to use new customer API. #2256
First pass at upgrade routine for #2256
Swap mixed up columns. #2256
Introduce exists() method. #2256
Add attach_payment() and increment_stats() methods. #2256
Fix get_column_by() method. #2256
INtroduce edd_get_payment_customer_id(). #2256
Increment stats when a purchase is completed. #2256
Whitespace