Add an implicit conversion from (Context => Unit) to ContextAction.
Extract JavaScriptShellConsoleProvider from JavaScriptShellConsole.

JavaScriptShellConsoleProvider does not depend on the internal state of
JavaScriptShellConsole. Extract it as a separate object.
Make BeyondJavaScriptEngine take pluginPaths in Seq[Path] instead of Seq[String].

Seq[Path] is more type-safe than Seq[String]. This patch also changes the
return type of BeyondConfiguration.pluginPaths to Seq[Path].
Reimplement JavaScriptTimerProvider with Akka system scheduler.

java.util.Timer is inefficient because it creates a thread for each timer
instance. Use Akka system scheduler to implement JavaScriptTimerProvider.
Rewrite RunScript example of Rhino in Scala.
Rewrite RunScript2 example of Rhino in Scala.
Rewrite RunScript3 example of Rhino in Scala.
Rewrite RunScript4 example of Rhino in Scala.