Merge pull request #20 from gkossakowski/fork-less

Remove scala-io fork.
Merge pull request #21 from gkossakowski/fork-less

Small cleanups and documentation of forks
Remove spray-json fork.

All Scala 2.11 compatibility patches has been merged upstream. Moreover,
spray-json upgraded to sbt 0.13.x which makes it easier to integrate into
dbuild.