Updated SBT formula, version 0.13.5, to use the standard sbt launcher script from typesafe

This resolves issue https://github.com/Homebrew/homebrew/issues/26083
This would need to be wrapped to a reasonable length, but... should we continue using a wrapper script and have it emit a warning if a `~/.sbtconfig` file exists? It seems unkind to break this without any notice.