Maven: Add missing junit dependency

Without this, `mvn package` fails due to missing dependency.

Change-Id: I30c7e1916a8df3ae1c4565127e5d8efb2cf7a390

pom.xml

diff --git a/pom.xml b/pom.xml
index abe8787..7ec228b 100644
--- a/pom.xml
+++ b/pom.xml
@@ -106,6 +106,12 @@
       <version>2.6.1</version>
       <scope>provided</scope>
     </dependency>
+    <dependency>
+      <groupId>junit</groupId>
+      <artifactId>junit</artifactId>
+      <version>4.11</version>
+      <scope>test</scope>
+    </dependency>
   </dependencies>
 
   <repositories>