Update OOjs UI to v0.2.3

Release notes:
 https://git.wikimedia.org/blob/oojs%2Fui.git/v0.2.3/History.md

Change-Id: Ia3d8a5a9df0efffd2b5cb1466e600cc0b77d7ef2
Merge "Update OOjs UI to v0.2.3"