UI freeze exception request: adjusting icons and CSS style

Binary package hint: ubiquity-slideshow-ubuntu

I am proposing a set of modifications to the visuals for the Ubuntu slideshow package.
Some of these changes spring from bug #552510, which covers centring the icons used in the slideshow, but there are a few other changes as well.

These are currently seen in lp:ubiquity-slideshow-ubuntu, revisions 260 to 261. (Sorry, jumped the gun a bit; I should have made a separate branch. Oh well).

First the CSS layout change:
 * Title block is slightly narrower. Before, the title could flow right up to the icon at the top right before wrapping to the next line. That is no longer the case; it now wraps much earlier in the line so there isn't so much visual noise up there. This means multi-line titles should (hopefully) wrap a bit more elegantly.
 * Increased spacing between individual lines.
 * Increased width of content; text is as far from the edge on the right as it is on the left side. This appears to nullify the net effect of the increased line spacing.

Then the icons:
 * The new personalize.png replaces the old accessibility icon. It is the "Change wallpaper" icon from the Humanity set. I decided this appealed to the idea of personalizing the desktop to fit one's personal wishes, where the previous icon provided a rather clinical feeling. The dash of aubergine gives the topic a nice jolt of life.
 * New media.png replacing the Rhythmbox icon. There were a lot of comments about the out of place Breathe icon, and it was somewhat difficult to align it elegantly. (Rhythmbox icons are all rather rectangular, the others we have are square. It looked funny). I went with the generic Media category icon from the Humanity set because it's one of the more pretty looking icons in that genre by default, and it is an icon people will recognize when they open the Applications menu.

Thank you!