Bug 22906: Minor corrections to plugins home page

Bug 22906: Minor corrections to plugins home page

This patch makes a few minor markup improvements to the plugins home
page and corrects some CSS introduced by Bug 22053 which was having
unintended consequences elsewhere.

To test, apply the patch and rebuild the staff client CSS.

 - You should have one or more plugins installed.
 - Go to Administration -> Manage plugins.
 - The "badges" for disabled and enabled should look correct.
 - Go to Tools -> Staged MARC management and click on an batch.
   - In the information about the batch, the labels should be bold.

Signed-off-by: Liz Rea <wizzyrea@gmail.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
(cherry picked from commit e9294c3cc20584adebb6d38451ebccce86a8f1aa)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>