Fix checkstyle errors when building archetype-generated apps

Checkstyle validation is now enabled by default in onos-dependencies
(archetypes' parent pom). We also add a reference to the archetypes' pom
to disable checkstyle, if needed.

Change-Id: I9b6e6cecf2d704f52ec1f118eae2aafd03cf0b9a
diff --git a/tools/package/archetypes/uitab/src/main/resources/archetype-resources/pom.xml b/tools/package/archetypes/uitab/src/main/resources/archetype-resources/pom.xml
index 7775946..3551265 100644
--- a/tools/package/archetypes/uitab/src/main/resources/archetype-resources/pom.xml
+++ b/tools/package/archetypes/uitab/src/main/resources/archetype-resources/pom.xml
@@ -20,7 +20,9 @@
   ~ See the License for the specific language governing permissions and
   ~ limitations under the License.
   -->
-<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
 
     <parent>
@@ -78,6 +80,15 @@
                 <groupId>org.onosproject</groupId>
                 <artifactId>onos-maven-plugin</artifactId>
             </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-checkstyle-plugin</artifactId>
+                <!-- Uncomment to disable checkstyle validation
+                <configuration>
+                    <skip>true</skip>
+                </configuration>
+                -->
+            </plugin>
         </plugins>
     </build>