Add typelevel/discipline project.

It's a dependency of spire so we would like to give it a warm welcome in
dbuild-covered family of projects!
Add spire to the dbuild config.

It almost builds completely with Scala 2.11. The one subproject that
crashes the compiler is "tests". It fails due to
https://issues.scala-lang.org/browse/SI-8425.
Merge remote-tracking branch 'typesafehub/master' into spire
Remove work-around from spire build definition.

The bug that was causing Scala compiler crash in spire's tests has been
fixed upstream. We can build entire spire now.
Remove unnecessary emphasis from comments.

Support for Scala 2.11 is becoming a default now. No need to emphasize that
anymore.
Merge pull request #24 from gkossakowski/spire

Add spire and discipline projects