Properties Editor / Mesh Data: 
* Give the uiLists a default size of 1, when we don't have any element in it. This saves some space.

Vertex Groups and Shape Keys list will jump to 5 as before when we have an element, due to the additional buttons, for the others, just grow with additional elements. 

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk@60735 954f8c5b-7b00-dc11-b283-0030488c597c