change default logger to dedicated one (#1064)

Fix test


Fix format

Update pytorch_lightning/__init__.py
Separate imports

pytorch_lightning/profiler/profiler.py

@@ -1,6 +1,5 @@
 import cProfile
 import io
-import logging as log
 import pstats
 import time
 from abc import ABC, abstractmethod
@@ -9,6 +8,8 @@ from contextlib import contextmanager
 
 import numpy as np
 
+from pytorch_lightning import _logger as log
+
 
 class BaseProfiler(ABC):
     """