Merge branch 'fix-nonetype-exception' of https://github.com/csparker247/pyexiftool into csparker247-fix-nonetype-exception

resolve bug in using the wrong common_args in the constructor.  in Pull request #5 by @csparker247

Author: sylikc

exiftool.py

@@ -317,7 +317,7 @@ def __init__(self, executable_=None, common_args=None, win_shell=True):
 		else:
 			raise TypeError("common_args not a list of strings")
 
-		self.no_output = '-w' in common_args
+		self.no_output = '-w' in self.common_args
 
 
 	def start(self):