Improve image thumbnailing and increase the size of Macro thumbnails
Summary:
Alternate proposal for D3635.
- Works better with small images.
- Produces a predictable thumbnail size.
- Somewhat reasonable output on 3000x10 images.
- Increase the size of Macro thumbnails to 240px.
Test Plan: {F20497}
Reviewers: vrana, chad
Reviewed By: vrana
CC: aran
Differential Revision: https://secure.phabricator.com/D3638