string fix for gnome-session

[William Jon McCann <william jon mccann gmail com>]

Hi,

We have a pretty glaring typo on the so-called fail whale screen.
This screen occurs if any required component fails and doesn't
restart.

While we hope you never see this screen, it is pretty unprofessional
to have an obvious misspelling there.

It was my fault and I'm hoping you let me fix it.

http://git.gnome.org/browse/gnome-session/tree/gnome-session/gsm-fail-whale-dialog.c#n283

Thanks,
Jon