Remove scala-arm fork

Changes that adapted scala-arm to Scala 2.11 has been merged upstream
so we don't need the fork anymore. Also, scala-arm switched to sbt 0.13.1
and we follow accordingly.
Ignore dbuild directory for all dbuild versions.

Add a pattern to .gitignore file that matches directories corresponding
to all dbuild versions.
Remove parboiled fork.

Scala 2.11 patches has been merged.
Merge pull request #16 from gkossakowski/fork-less

Less forking on our dbuild configuration for Scala 2.11.