fix pom

pom.xml

@@ -14,5 +14,20 @@
     <module>./webmagic-samples/</module>  
   </modules>  
 
+  <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>3.1</version>
+                <configuration>
+                    <source>1.6</source>
+                    <target>1.6</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+
 
 </project>