Add DO commonalities
Add DO commonalities

Fixes #235.
Ref #231 for `createImage` on DO.

dionjwa/pkgcloud,apla/pkgcloud,mdsummers/pkgcloud,Hopebaytech/pkgcloud,songanbui/pkgcloud,Phanatic/pkgcloud,bunglestink/pkgcloud,DonSchenck/pkgcloud,hacor/pkgcloud,mcanthony/pkgcloud,Phanatic/pkgcloud,pkgcloud/pkgcloud,temka1234/pkgcloud,andrewsomething/pkgcloud