fixes #162 bump up java version to 1.8

Author: stevehu

pom.xml

@@ -58,7 +58,7 @@
         </repository>
     </distributionManagement>
     <properties>
-        <java.version>1.6</java.version>
+        <java.version>1.8</java.version>
         <java.testversion>1.7</java.testversion>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <version.jackson>2.9.9</version.jackson>