=sam update leveldb dependencies and doc links

(cherry picked from commit 8291bc0aca504851d0619815c98c760a7d458d18)

akka-samples/akka-sample-persistence-java-lambda/build.sbt

@@ -9,6 +9,8 @@ javacOptions in compile ++= Seq("-encoding", "UTF-8", "-source", "1.8", "-target
 javacOptions in doc ++= Seq("-encoding", "UTF-8", "-source", "1.8", "-Xdoclint:none")
 
 libraryDependencies ++= Seq(
-  "com.typesafe.akka" %% "akka-persistence" % "2.4-SNAPSHOT"
+  "com.typesafe.akka" %% "akka-persistence" % "2.4-SNAPSHOT",
+  "org.iq80.leveldb" % "leveldb" % "0.7",
+  "org.fusesource.leveldbjni" % "leveldbjni-all" % "1.8"
 )
 

akka-samples/akka-sample-persistence-java-lambda/src/main/resources/application.conf

@@ -1,3 +1,6 @@
+akka.persistence.journal.plugin = "akka.persistence.journal.leveldb"
+akka.persistence.snapshot-store.plugin = "akka.persistence.snapshot-store.local"
+
 akka.persistence.journal.leveldb.dir = "target/example/journal"
 akka.persistence.snapshot-store.local.dir = "target/example/snapshots"
 

akka-samples/akka-sample-persistence-java-lambda/tutorial/index.html

@@ -28,7 +28,7 @@ Custom storage locations for the journal and snapshots can be defined in
 <h2>Persistent actor</h2>
 <p>
 <a href="#code/src/main/java/sample/persistence/PersistentActorExample.java" class="shortcut">PersistentActorExample.java</a>
-is described in detail in the <a href="http://doc.akka.io/docs/akka/2.3-SNAPSHOT/java/lambda-persistence.html#event-sourcing-java-lambda" target="_blank">Event sourcing</a>
+is described in detail in the <a href="http://doc.akka.io/docs/akka/2.4-SNAPSHOT/java/lambda-persistence.html#event-sourcing-java-lambda" target="_blank">Event sourcing</a>
 section of the user documentation. With every application run, the <code>ExamplePersistentActor</code> is recovered from
 events stored in previous application runs, processes new commands, stores new events and snapshots and prints the
 current persistent actor state to <code>stdout</code>.