Sync oox -> writerfilter namespace prefixes

Change-Id: Ifbcb7716640cd05d4b98eef22f9ddf49f3bd79aa
Sync oox -> writerfilter alias for generic VML

See 656ab07b2924dd2703f31f460c8586c375c7878a (Sync oox -> writerfilter
alias for wordprocessingml, 2014-08-10).

Change-Id: I5179961b683473a502693923422171bb274fc845