[Bug Fix] Add missing transforms in __init__.py (open-mmlab#260)

Author: xvjiarui

mmseg/datasets/pipelines/__init__.py

@@ -4,11 +4,13 @@
 from .loading import LoadAnnotations, LoadImageFromFile
 from .test_time_aug import MultiScaleFlipAug
 from .transforms import (Normalize, Pad, PhotoMetricDistortion, RandomCrop,
-                         RandomFlip, Resize, SegRescale)
+                         RandomFlip, RandomRotate, Rerange, Resize, RGB2Gray,
+                         SegRescale)
 
 __all__ = [
     'Compose', 'to_tensor', 'ToTensor', 'ImageToTensor', 'ToDataContainer',
     'Transpose', 'Collect', 'LoadAnnotations', 'LoadImageFromFile',
     'MultiScaleFlipAug', 'Resize', 'RandomFlip', 'Pad', 'RandomCrop',
-    'Normalize', 'SegRescale', 'PhotoMetricDistortion'
+    'Normalize', 'SegRescale', 'PhotoMetricDistortion', 'RandomRotate',
+    'Rerange', 'RGB2Gray'
 ]