Bug Fix: Submenu 'Jetpack' display with additional spaces in WP 4.0 beta

The submenu ‘Jetpack’ had the class ‘menu-top’ applied to it which
caused the submenu to appear with weird spacing.
Defining an additional submenu fixes this issue that replaces the auto
generated one fixes this issue.
Merge branch 'master' of github.com:Automattic/jetpack