Replace the Star ratings in the dashboard with dashicons ratings.
This also moves the ratings to only displaying full, half, or empty stars (ie. 3.0, 3.5, 4.0, no 3.7 ratings - which are rounded).
Fixes #26170

Built from https://develop.svn.wordpress.org/trunk@26380


git-svn-id: http://core.svn.wordpress.org/trunk@26280 1a063a9b-81f0-0310-95a4-ce76da25c4cd