* changed zeromq-scala-binding library
* modified build-release task to include distributions from cross builds
* removed tar-zip step from release script, because tgz package is not used from the website
* release script now releases for all crossScalaVersions
* dry run is the default now
Simpler than what was there before. Just a single zip file
is being created. Extending this should be coordinated
with Josh's work on the integrated typesafe stack build.
Also add caching to rstdoc task.