Expand Elasticsearch groovy sandbox

Elasticsearch 1.3 comes with groovy as a scripting language and it is
sandboxed a tiny bit too tight for Cirrus.  This expands the sandbox slightly.
It does not disable dynamic scripting - we can't do that until we've fully
ported Cirrus to groovy and we can't do that until 1.3 is already live.

Technically this will change the groovy sandbox for all Elasticsearch's we
have in production but the change isn't going to hurt anything.

Change-Id: Iebd0a94888140a836189580c38ee4666dc5df8b2