Add leaf cache

Change-Id: Ib630e0327cf64c246c3648361e5a6844ea30cf3a
diff --git a/pom.xml b/pom.xml
index 88e1120..79974de 100644
--- a/pom.xml
+++ b/pom.xml
@@ -35,7 +35,7 @@
 
   <groupId>de.ids-mannheim.korap.krill</groupId>
   <artifactId>Krill</artifactId>
-  <version>0.64.5</version>
+  <version>0.64.6</version>
   <packaging>jar</packaging>
 
   <name>Krill</name>
@@ -163,6 +163,13 @@
       <version>1.1</version>
     </dependency>
 
+    <!-- Caffeine -->
+    <dependency>
+      <groupId>com.github.ben-manes.caffeine</groupId>
+      <artifactId>caffeine</artifactId>
+      <version>3.1.8</version>
+    </dependency>
+
     <!-- Jersey -->
     <dependency>
       <groupId>org.glassfish.jersey.containers</groupId>