Standardize rendering of atom type names like "Article" and "Class"

Summary: Ref T988. This was sort of hard-coded in one place and not done properly in another. Do it consistently.

Test Plan: Looked at atom list; looked at atom view. Saw "Article", "Class" rendered correctly.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T988

Differential Revision: https://secure.phabricator.com/D6821