S-A-T-U-R-D-A-Y! For many readers, that chant will undoubtedly conjure up images of a group of tartan-clad Scotsmen, whose catchy, hook-filled 45s led hordes of screaming teenagers and teenyboppers to the dance floor (alongside adults with discerning taste in irresistible pop music, of course!). The history of The Bay City Rollers is being celebrated by the fine folks of the U.K.’s Salvo Records with the October 4 release of a deluxe four-disc anthology they’ve quite accurately called Rollermania (Salvo SBX451). The enterprising label has already given us similar career-spanning box sets for bands as diverse…