Create openstack swift Directory with metadata does not work

[plribeiro3000]

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In this doc, it was mentioned that create method support a :metadata key.

However, the create method does not really pass the metadata into headers when the put_container method is called in directory class

Any reason why this is happening if it is not a bug?

Original issue opened by @dixia at fog/fog#3526

[plribeiro3000]

cc/ @dixia @TerryHowe @geemus