Update OOjs UI to v0.1.0-pre (571f26d0ab)

New changes:
8ada8cd OOUI PHP: Use 'OOUI' namespace instead of 'OoUi' class name prefix
4c56ad5 More random documentation fixes
3eb27b9 Recompute ComboBox selection when adding/removing items
e596cc5 Followup d3367bb: make FieldsetLayout <label>s display: block;

Change-Id: I5525a6285f4f24fa0fd997482c1735bef5639dc6