README: mention ruby/sass dependency
README: mention ruby/sass dependency

nickel715/meshviewer,xf-/meshviewer-1,yayachiken/hopglass,FreiFunkMuenster/meshviewer,rubo77/meshviewer,FreifunkBremen/meshviewer-ffrgb,kgbvax/meshviewer,ffnord/meshviewer,Freifunk-Rhein-Neckar/meshviewer,mayflower/meshviewer,srauscher/hopglass,yayachiken/hopglass,freifunkMUC/meshviewer,gherber/hopglass,mayflower/meshviewer,nonchip/meshviewer,plumpudding/hopglass,srauscher/hopglass,TVLuke/meshviewer,TVLuke/meshviewer,ffnord/meshviewer,Freifunk-Troisdorf/meshviewer,nonchip/meshviewer,gherber/hopglass,xf-/meshviewer-1,FreiFunkMuenster/meshviewer,hopglass/hopglass,rubo77/meshviewer-1,tcatm/meshviewer,Little-Ben/meshviewer,nonchip/meshviewer,rubo77/meshviewer,rubo77/meshviewer-compilation,freifunk-fulda/meshviewer,freifunk-mwu/meshviewer,freifunkMUC/meshviewer,Freifunk-Luxembourg/hopglass,ffac/meshviewer,kgbvax/meshviewer,Freifunk-Rhein-Neckar/meshviewer,nickel715/meshviewer,hopglass/ffrgb-meshviewer,tcatm/meshviewer,Freifunk-Rhein-Neckar/meshviewer,max-weller/meshviewer,FreifunkBremen/meshviewer-ffrgb,freifunk-fulda/meshviewer,rubo77/meshviewer-1,ffac/meshviewer_old,hopglass/ffrgb-meshviewer,rubo77/meshviewer-compilation,FreifunkMD/Meshviewer,freifunk-mwu/meshviewer,Little-Ben/meshviewer,ffac/meshviewer,hopglass/hopglass,freifunk-mwu/meshviewer,ffrgb/meshviewer,ffac/meshviewer_old,Freifunk-Luxembourg/hopglass,ffrgb/meshviewer,tcatm/meshviewer,Skrupellos/meshviewer,Skrupellos/meshviewer,max-weller/meshviewer,FreifunkMD/Meshviewer,FreiFunkMuenster/meshviewer,TVLuke/meshviewer,plumpudding/hopglass,Freifunk-Troisdorf/meshviewer,ffnord/meshviewer,ffac/meshviewer