Missing translations for Theme Tags

[dd32]

It seems that the Theme API was updated to add some more tags, unfortunately we don't seem to have added the translations for them in core(in get_theme_feature_list()). (You'll see them on the Theme install page as 'featured-image' rather than 'Featured Image')

strings in question:

 gray - 'Gray' Exists
 featured-image-header - No existing reasonable string
 featured-images - we have 'Featured Image'
 full-width-template - No existing reasonable string
 post-formats - Closest we have is 'Post Format:' and _x('Format', 'post format')

We have however just hit string freeze.. So if there's any existing strings which can be used, might as well use them (Gray for example).

Setting as 3.2 for others review.

[nacin]

I figured this was done, but it turns out that #17359 is languishing in awaiting review.