Use Java 7 to use the same Java version as Gerrit core

Change-Id: Ibab118f36aa818a171a374af6f385e9d7a2f7219
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>

pom.xml

diff --git a/pom.xml b/pom.xml
index fbdf80e..92da033 100644
--- a/pom.xml
+++ b/pom.xml
@@ -38,8 +38,8 @@
         <artifactId>maven-compiler-plugin</artifactId>
         <version>2.3.2</version>
         <configuration>
-          <source>1.6</source>
-          <target>1.6</target>
+          <source>1.7</source>
+          <target>1.7</target>
           <encoding>UTF-8</encoding>
         </configuration>
       </plugin>