Seperate JavaScript engine package.

Rhino helper classes and JavaScript library extensions are moved to
beyond.engine.javascript package.
Change the package paths of JavaScript files.

The previous patch has a bug. Console and Event library use hardcoded package
paths, so these paths must have been changed too.
Move beyond package to a sub-project.

If beyond package is in the base projet, sub-projects cannot depend on beyond
because it creates a circular dependency. The base project aggregates the
sub-project and the sub-project depends on the base project.
Update native library path.

The native library path needs to be updated because Beyond package is moved to
core sub-project.
Extract user and session management as a sub-project.

logig and logout URLs are changed:
- /session/login -> /user/login
- /session/logout -> /user/logout
Move beyondAdmin to modules/admin.
Add scalaz to SBT library dependencies.
Use conditional operator ? provided by scalaz.