Replaced calls of get(foo, None) -> get(foo)

If no default value is specified, the get method of dictionaries
defaults to 'None' already.
So removing the 'None' argument to make the code more clean and
readable.

Change-Id: I2f29315488d515aa2837d06ea59ab41e8ca05fc8
Merge "Replaced calls of get(foo, None) -> get(foo)"