remove tomcat7-maven-plugin

pom.xml

@@ -159,11 +159,6 @@
           <warSourceExcludes>WEB-INF/classes/**/*.*,WEB-INF/lib/*.jar</warSourceExcludes>
         </configuration>
       </plugin>
-      <plugin>
-        <groupId>org.apache.tomcat.maven</groupId>
-        <artifactId>tomcat7-maven-plugin</artifactId>
-        <version>2.2</version>
-      </plugin>
       <plugin>
         <groupId>org.seasar.dbflute</groupId>
         <artifactId>dbflute-maven-plugin</artifactId>