Update to Lucene 4.8

Closes #24.
(cherry picked from commit 1596bf6)

Author: dadoonet

pom.xml

@@ -33,7 +33,7 @@
 
     <properties>
         <elasticsearch.version>2.0.0-SNAPSHOT</elasticsearch.version>
-        <lucene.version>4.7.0</lucene.version>
+        <lucene.version>4.8.0</lucene.version>
         <tests.jvms>1</tests.jvms>
         <tests.shuffle>true</tests.shuffle>
         <tests.output>onerror</tests.output>