Remove bottom: 0 from app-navigation-entry-utils to prevent the utils form overlapping the whole element....

... This happens for instance if a folder has entries -> the menu expands to the very bottom and overlaps all entries and makes them impossible to click. Without the bottom: 0 it just uses its normal height which is fine.

@jancborchardt @raghunayyar @MorrisJobke @jbtbnl @georgehrke