Remove trailing space in pmahomme common CSS

Signed-off-by: Ann + J.M <phpMyAdmin@ZweiSteinSoft.de>
Add bottom border to pmahomme top menu container

Signed-off-by: Ann + J.M <phpMyAdmin@ZweiSteinSoft.de>
Add ChangeLog entry for rfe #1500

Signed-off-by: Ann + J.M <phpMyAdmin@ZweiSteinSoft.de>
rfe #1500 [interface] Add bottom border to top menu container