Fix front page sample.
Change group to “io.ratpack”.
Don't wrap Javadoc comments.
Minor javadoc formatting.
Fix formatting.
Fix javadoc.
Configure our nullable annotation.
Improve the Jackson stuff.
Introduce a Groovy specific Context interface which allows Closure API specialisations.

Used this to implement a better blocking API for Groovy.
Rename the Groovy Context subclass to GroovyContext.
Rename the groovy blocking interface to GroovyBlocking.
Rename the groovy chain subclass to GroovyChain.
Rename the groovy chain subclass to GroovyChain.
Javadoc.
Bump the Groovy version and fix the docs with the new compile static fixes.
Bump the Groovy version and fix the docs with the new compile static fixes.