add a yapf style for all our repos

.style.yapf

+[style]
+# https://github.com/google/yapf#knobs
+based_on_style = google
+spaces_before_comment = 5
+split_before_logical_operator = True
+column_limit = 119
+no_spaces_around_selected_binary_operators = True
+split_before_dot = True
+join_multiple_lines = True