Fix up translations after string freeze break

Commit 1b334350
fixed a problem with GDM in low resolution machines.

While this commit is a valid and important bug fix,
it unfortunately, broke string freze.

See:

http://mail.gnome.org/archives/gdm-list/2010-June/msg00014.html

This commit manually fixes up all the msgids and msgstrs so that
the old transitions still work.

Note, some of the translations get plurality wrong for "Session"
(like the original C string did before commit 1b334350).  That's
not optimal, but not any worse than before.