I updated the Gradle script to use 1.8.3 because it's what I use. It compiled fine, but you might want to keep using an older version. I also updated to jUnit 4.10, which shouldn't be a problem.
I also added SLF4J; the servlet now has a logger instead of using println. The App also has a logger, as does the request delegate, which is cool because now the scripts can use logger.info, logger.error, etc.
Upgrade to Groovy 1.8.3 and jUnit 4.10
Added SLF4J 1.6.3 as a compile time dependency
Added slf4j-simple as a testRuntime dependency
Added a logger
Added slf4j-simple via @GrabConfig
I don't know if this will run on Groovy 1.7.1 which is the version that's originally used for RatPack...
You might want to keep using 1.7, I don't know.
Upgrading to jUnit 4.10 shouldn't be a problem
JUnit update, Groovy version update, and logging approved. We may move to log4j rather than slf in the future but this is a good step. Nice job, chochos!
The nice thing about SLF4J is that you can use log4j as a backend, or logback, or JUL; you decide at runtime. But I still don't know of an easy way to configure it; I tried using @Grab in the script and it didn't work, that's why I ended up using @GrabConfig in the startup script.