changes sbt download page to use http:// #6754 (#6755)
changes sbt download page to use http:// #6754 (#6755)

currently the link used https:// however sbt uses github pages which results in a broken certificate.
Shruti9520/playframework,aradchykov/playframework,rajeshpg/playframework,mkurz/playframework,richdougherty/playframework,Shenker93/playframework,ktoso/playframework,rajeshpg/playframework,Shruti9520/playframework,mkurz/playframework,richdougherty/playframework,benmccann/playframework,wegtam/playframework,playframework/playframework,richdougherty/playframework,hagl/playframework,marcospereira/playframework,marcospereira/playframework,rajeshpg/playframework,marcospereira/playframework,zaneli/playframework,wsargent/playframework,hagl/playframework,benmccann/playframework,hagl/playframework,Shenker93/playframework,Shruti9520/playframework,zaneli/playframework,ktoso/playframework,ktoso/playframework,marcospereira/playframework,playframework/playframework,rajeshpg/playframework,mkurz/playframework,aradchykov/playframework,benmccann/playframework,wegtam/playframework,hagl/playframework,Shruti9520/playframework,mkurz/playframework,Shenker93/playframework,wegtam/playframework,ktoso/playframework,richdougherty/playframework,zaneli/playframework,aradchykov/playframework,benmccann/playframework,aradchykov/playframework,zaneli/playframework,Shenker93/playframework,wegtam/playframework,playframework/playframework,wsargent/playframework,wsargent/playframework,wsargent/playframework