Fix the byline if authorDefault is explicitly provided.

layouts/partials/byline.html

@@ -5,6 +5,8 @@
 }}{{     .Scratch.Set "author" .Site.Params.authorHyperling
 }}{{ else if or (eq $author "authorhypervegan") (eq $author "hypervegan")
 }}{{     .Scratch.Set "author" .Site.Params.authorHyperVegan
+}}{{ else if or (eq $author "authordefault") (eq $author "default")
+}}{{     .Scratch.Set "author" .Site.Params.authorDefault
 }}{{ else if and ($author) (not (eq $author ""))
 }}{{     .Scratch.Set "author" $author
 }}{{ else