[releng] PR #6968: Add fedora-27 and -28 keys to sigulsign

[Mohan Boddu]

mohanboddu merged a pull-request against the project: `releng` that you are following.

Merged pull-request:

``
Add fedora-27 and -28 keys to sigulsign
``

https://pagure.io/releng/pull-request/6968