UIFe: Checkbox header image is wrong

[Daniel Manrique]

Hello!

I'm writing again to request a UI Freeze Exception for checkbox. Currently
checkbox in Ubuntu has a wrong header image as can be seen here:

http://people.canonical.com/~roadmr/header-bad.png

We'd like to replace it with this, which is present in the development version
but got left behind during a merge due to an oversight (apologies):

http://people.canonical.com/~roadmr/header-good.png

This new header image works better with the default Ubuntu theme and also takes
care of usability concerns, where testers were unsure if the "icons" on the old
header image are clickable.

No translatable strings are involved or changed; the "system testing"  string on
the right is already in the .pot file and didn't change. Also there's no change
to checkbox's functionality.

The corresponding bug report is this one:

https://bugs.launchpad.net/ubuntu/+source/checkbox/+bug/1044035

Thanks!

- Daniel