sbt build: remove redundant setting

`name` is set in project/Build.scala, so setting it in build.sbt isn't
needed
re-add Scaladoc support on headless branch

I'd removed it back when headless was just a sandbox branch, but now
that it's become a real line of development, seems like we should have
it
Merge remote-tracking branch 'origin/headless' into sbt-0.13

Conflicts:
	build.sbt