Update to Gerrit 2.9 API and use Java 7

Change-Id: Ic69ddd083d5fca9673c2bd5ca21c79d3d62d11fb
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>

pom.xml

diff --git a/pom.xml b/pom.xml
index 002a5fa..0fe62b4 100644
--- a/pom.xml
+++ b/pom.xml
@@ -20,7 +20,7 @@
   <parent>
     <groupId>com.googlesource.gerrit.plugins.its</groupId>
     <artifactId>hooks-its-parent</artifactId>
-    <version>2.8-SNAPSHOT</version>
+    <version>2.9-SNAPSHOT</version>
   </parent>
   <artifactId>hooks-jira</artifactId>
   <packaging>jar</packaging>
@@ -34,6 +34,16 @@
   <build>
     <plugins>
       <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-compiler-plugin</artifactId>
+        <version>2.3.2</version>
+        <configuration>
+          <source>1.7</source>
+          <target>1.7</target>
+          <encoding>UTF-8</encoding>
+        </configuration>
+      </plugin>
+      <plugin>
         <groupId>org.codehaus.mojo</groupId>
         <artifactId>axistools-maven-plugin</artifactId>
         <version>1.3</version>