Modify swissknife to support certificate rotation for seaworthy

[eak13]

As an operator, I would like to have swissknife updated to support certificate rotation for Seaworthy, so that I have a more current set of certificate rotation tools for a Network Cloud 2,x site.

Swissknife currently supports cert rotation for a NC 1.9x site implementation. This issue is to provide the same functionality in Seaworthy so it can be used as a basis for supporting NC2.x sites and will greatly eliminate the arduous manual effort (which can take up to 3 days) to manage certificates independent of a tool. This will greatly increase the usability of Airship 1.0 & will help bridge the gap until Airship 2.0 is generally available.

Issue #1 may provide enough of a MVP where a user could potentially take the documentation and make the configuration changes themselves, but ideally having this reference implementation will greatly reduce the burden on the user.