add sql cli and explain it in the readme

capsulflask/db_model.py

@@ -146,12 +146,12 @@ class DBModel:
 
   def list_payments_for_account(self, email):
     self.cursor.execute(""" 
-      SELECT  dollars, invalidated, created
+      SELECT id, dollars, invalidated, created
       FROM payments WHERE payments.email = %s""", 
       (email, )
     )
     return list(map(
-      lambda x: dict(dollars=x[0], invalidated=x[1], created=x[2]), 
+      lambda x: dict(id=x[0], dollars=x[1], invalidated=x[2], created=x[3]), 
       self.cursor.fetchall()
     ))