pool: Replace parboiled library with grappa

The author of parboiled has abandoned this version and moved on to parboiled2.
The new version is unfortunately a Scala only project, leaving us Java users
behind. parboiled1 doesn't support Java 8. Other users have forked the project
and added Java 8 support. The new project is called grappa.

Target: trunk
Require-notes: no
Require-book: no
Acked-by: Karsten Schwank <karsten.schwank@desy.de>
Patch: https://rb.dcache.org/r/7429/