Theme Installer fixes:
 * Better more filters section. props sonjanyc for some mockups.
 * Better handling of no results.
 * Use # for hrefs.

props matveb.
see #27055.

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git-svn-id: http://core.svn.wordpress.org/trunk@27727 1a063a9b-81f0-0310-95a4-ce76da25c4cd