Update p12n extract and view: remove metro, improve OS portability

## scripts/p12n_extract.py
* Remove Metro checks (```check_p12nmetro``` was already disabled).
* Remove concatenations for paths, use ```os.path.join``` and ```os.sep```, avoid using ```path``` as variable name.
* Fix coding style consistency: remove unnecessary parenthesis, use double quotes, ```and``` instead of ```&```.

## views/productization.php
Remove Metro from view