Add LabelUtil.
Replace mx:ComboBox with s:DropDownList.
Use LabelUtil to dynamically size s:DropDownList & s:ComboBox to longest item.
Clean up.

* Rename LabelUtil#findfindLongestItemLabel to LabelUtil#findLongestLabel.

* Apply formatting.
Merge branch '#39/replace-halo-combo-box' into develop