String changes in control center

[Jens Granseuer <jensgr gmx net>]

Hi,

here are some last minute string change announcements before the
freeze.

bug 547276 [0]: don't use the term "accelerator"
bug 545256 [1]: improve the tooltip for the a11y settings dialog

Cheers,
Jens

[0] http://bugzilla.gnome.org/show_bug.cgi?id=547276
[1] http://bugzilla.gnome.org/show_bug.cgi?id=545256