New committer (ports): Austin Shafer (ashafer)

Complete steps 1-4 from the Committer's Guide, section 7.1 (For New
Committers):

1. Add an Author Entity.
2. Update the List of Developers and Contributors.
3. Add a News Item.
4. Add a PGP Key.

Approved by: kbowling (mentor)
Differential Revision: https://reviews.freebsd.org/D48694