Uses background-size: cover (like Medium) to scale the image
Sets project poster as background-image for greater control
Sets max-width of project poster to 1600px (dark background)
Changes hover animation for project icons
Enables new background + logo for project poster
Deprecates old style (single image)
Documents in README
Updates chanjo resources to adapt to new project poster format
PNG => SVG
Merge pull request #18 from SciLifeLab/robin/restrict-poster-image

Restricts project poster to 1600px