(chore) Delete deprecated versions of static

This will remove the extra `static_file` and `staticfile` crates from the documentation.

`static` will be added to the documentation by Travis when it is merged.

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@reem, whenever you merge iron/static-file#52 and iron/static#1, you should merge this to remove old documentation. I've accidentally merged it once already, but reverted it so as to wait for upstream changes.