Add missing value 'mirror_complete' to mirroring_policy param.

[vhsantos]

As mentioned on the issue #170, mirroring_police parameter from repositories accept 03 values (additive, mirror_complete, mirror_content_only), but the mirror_complete was missing.

Additional, updated the documentation to include this parameter too.

[vhsantos]

Hi @lhw

may you can check and approve theses simple PR too ??

[lhw]

Could you use the autodoc tool for the documentation. This is not something that is touched manually. After that please ping me. But I do have to find a better way to get notifications on GH. They just get lost among my work notifications

[bitkeks]

Code LGTM, three fields according to Katello API docs: Must be one of: additive, mirror_complete, mirror_content_only.

[bitkeks]

After re-testing this, just adding the parameter is not enough.

Spec says: Mirror Complete: a sync behaves exactly like "Mirror Content Only", but also mirrors metadata as well. This is the fastest method, and preserves repository signatures, but is only supported by yum and not by all upstream repositories.

This only works on yum-based repositories and throws an error on deb repositories. So we'll need to add a check for the repo type and only then allow mirror_complete to be used on yum repos.