update maven compiler plugin to target 1.6 since we dont support 1.5 (#444)

Author: jeanbza

pom.xml

@@ -306,8 +306,8 @@
           <artifactId>maven-compiler-plugin</artifactId>
           <version>2.3.2</version>
           <configuration>
-            <source>1.5</source>
-            <target>1.5</target>
+            <source>1.6</source>
+            <target>1.6</target>
           </configuration>
         </plugin>
         <plugin>