user_registration button with no link

[Jim Tittsler]

In the earlier WordPress course with user logins, the user_registration button was a link in the wiki and the b18123c addition codified that assumption. In a recent course @Mackiwg tried to use a registration button that was not a link in the wiki, so the snapshot tool should get a little smarter to remove this restriction.

[Jim Tittsler]

Add user_registration button with no link.

The earlier courses presumed the user_registration button contained a link. This removes that assumption and allows a button to contain text only.

Resolves #28

→ <<cset bd74529b40ab>>