odt: Seems styles.xml and meta.xml are not mandatory

At least libreoffice opens the file from bug 324241 that has neither of them.
With this change we open it too, it looks crap when compared to libreoffice,
but that's just because our ooo generator needs to die in favour of a calligra one.

BUGS: 324241
FIXED-IN: 4.11.5