Online installs don't get root-overlay files, so the antergos-logo
at hicolor icon theme paths (/usr/share/icons/hicolor/{128,256}x{128,256}/apps/
and /usr/share/pixmaps/) was missing on online-installed systems.
Add transparent logo PNGs at proper sizes to the wallpapers package,
which is already included in the online netinstall group.
Bump pkgrel to 7.