keyring: change display name for passwords to be more human-readable

keyring: change display name for passwords to be more human-readable

Apparently people complained that when they opened seahorse to look at
their passwords they were greeted by nice display names for keys for
wireless networks saved by NetworkManager, and ugly keys for secret
parameters saved by mission-control. Let's fix this now then and shut
these people up.

gnome-keyring finds passwords on the parameters set in the schema, so
the display name really is only to show in seahorse. We can set
anything we want here.

Signed-off-by: Jonny Lamb <jonnylamb@gnome.org>