Document the need for `appendScalacOptions` hack.

Link to an issue in dbuild which describes the purpose of
`apppendScalacOptions` hack we have in the config.
Upgrade to Scala 2.11.2 used for extraction.

Dbuild overrides Scala version during extraction phase. Let's move to
the latest, stable Scala release.
Move away from custom Lift fork.

Let's switch to Lift upstream, the 3.0-M2 version which is the latest
tagged release.
Switch to tagged releases of a few projects.

As part of a cleanup, we are dropping forks that got introduced around
Scala 2.11. release. Many projects have caught up and we can switch to
following upstream and rely on tagged releases.
Merge pull request #63 from gkossakowski/cleanups

Cleanups in dbuild config