Updates to Finnish and Swedish translations. Strings improvements.

- Changed English strings to use 'Wi-Fi' consistently. Before, there was a mixture of 'wifi', 'Wifi' and 'Wi-Fi'. 'Wi-Fi' is the registered trademark and it's what Google seems to use at least in the Settings and Drive apps.

- Changed the wording of the new image fetch mode setting to be a bit simpler and more in line with Google's design guidelines. "Load images automatically" used to be a setting in Mozilla/Firefox, so maybe some users are familiar with it (it's since been removed from the Firefox UI).

- updated Finnish and Swedish strings