Don't use type-aliases for CreateOpts and UpdateOpts.

They make the godoc output much less readable. The duplication is minimal, and I think having the documentation be better is a worthwhile tradeoff.
Switch this patch to simply make commonOpts public
Explanatory comment
Merge pull request #295 from alex/expose-create-and-update-opts

Don't use type-aliases for CreateOpts and UpdateOpts.