overriding meta tags that use property="..." attributes rather than name="..."


Hi, please find a suggested amendment whereby existing tags are searched for by "property" value in addition to "name". The use case is to allow (for example) a default og:image tag to be specified in the layout, and then overridden in the views.

Without this fix, the current behaviour is simply to output multiple og:image meta tags.

Thanks,
Kieran