Add command to execute script

Add a command which can execute arbitrary script

> script /path/to/script
> script -groovy println 'Hello'
> script print("hello")
> script <<EOT
println(nodeStore.getRoot())
EOT

For the last the script would be assumed to be javascript by default. Later we can enhance the Console to read multi line string use herestring

The ConsoleSession can be exposed as bind variable and can be used by script to access the runtime