Save dive computer device name.

Save dive computer device name.

It is really annoying to have to type the device name each time you need
to import a dive from your computer, if you are not using the default
device name. This will save the device name in the configuration file and
matches the logic currently used to save the dive computer name in the
configuration file.

Signed-off-by: Terrance Stanfield <t@hollowcranium.com>