McdAccount: set_parameter: ref the account across the gnome-keyring call
McdAccount: set_parameter: ref the account across the gnome-keyring call

Otherwise, the account won't necessarily still be there when we return...

Reviewed-by: Jonny Lamb <3d1fb3642aaab2ff70e3392a5ab916bf99eed6a3@collabora.co.uk>

freedesktop-unofficial-mirror/telepathy__telepathy-mission-control,freedesktop-unofficial-mirror/telepathy__telepathy-mission-control,freedesktop-unofficial-mirror/telepathy__telepathy-mission-control,freedesktop-unofficial-mirror/telepathy__telepathy-mission-control