Implemented predefined VC caching and added VC reference tests.

Change-Id: I84ad56b375f8b076ad92e493775993fc0580249f
diff --git a/full/src/main/resources/kustvakt.conf b/full/src/main/resources/kustvakt.conf
index 22e7e14..d7fbf7d 100644
--- a/full/src/main/resources/kustvakt.conf
+++ b/full/src/main/resources/kustvakt.conf
@@ -5,6 +5,8 @@
 krill.index.commit.log = log/krill.commit.log
 krill.index.commit.auto = 500
 krill.index.relations.max = 100
+## Directory path of virtual corpora to cache
+krill.namedVC = vc
 
 ## LDAP
 ldap.config = file-path-to-ldap-config