add PolyScheduler

Author: likyoo

change_detection_pytorch/utils/lr_scheduler.py

@@ -142,10 +142,9 @@ def __init__(self,
             raise TypeError('{} is not an Optimizer'.format(
                 type(optimizer).__name__))
         self.optimizer = optimizer
+        self.power = power
         self.by_epoch = by_epoch
-        self.epochs = epochs
         self.min_lr = min_lr
-        self.power = power
 
         # Validate total_steps
         if by_epoch: