Handle FileNotFoundError with proper error message

Using `IOError` for compatibility, from Python 3.3 `IOError` is alias of `OSError`
https://stackoverflow.com/a/28633573/6202405

Checking the errno of 'No such file or directory' so that only that exception will be catched.
https://docs.python.org/2/library/errno.html
https://stackoverflow.com/a/39414133



Signed-off-by: Bhavin Gandhi <bhavin7392@gmail.com>