Update /firefox/new screenshows for Australis
Bug 977465
Add high-res screenshots for /firefox/new page
Bug 977465
Note that the high-res linux and windows screenshots are just direct
copies of the normal resolution images, as high-res sources are not
available.
Cache-bust new image
Optimize high-res /new screenshot with ImageAlpha
Used Median Cut (pngquant) method with 256 colors (Dithered)
Merge pull request #1902 from sgarrity/bug-977465-new-australis-screenshots

Update /firefox/new screenshots for Australis