Implemented referencing cached collection.

Change-Id: I02f2ee84b3f8e50c5632efc9363eb87d97a754f8
diff --git a/pom.xml b/pom.xml
index 5b72473..45ed86f 100644
--- a/pom.xml
+++ b/pom.xml
@@ -35,7 +35,7 @@
 
 	<groupId>de.ids_mannheim.korap</groupId>
 	<artifactId>Krill</artifactId>
-	<version>0.57.0</version>
+	<version>0.58.0</version>
 	<packaging>jar</packaging>
 
 	<name>Krill</name>
@@ -106,6 +106,12 @@
 			<artifactId>jul-to-slf4j</artifactId>
 			<version>1.7.25</version>
 		</dependency>
+		
+		<dependency>
+		    <groupId>net.sf.ehcache</groupId>
+		    <artifactId>ehcache</artifactId>
+		    <version>2.10.5</version>
+		</dependency>
 
 		<!-- SQLite for database connection tests -->
 		<dependency>