Spring Boot JSP支持和main启动

<!-- servlet依赖. -->
<dependency>
   <groupId>javax.servlet</groupId>
   <artifactId>javax.servlet-api</artifactId>
   <scope>provided</scope>
</dependency>
<dependency>
   <groupId>javax.servlet</groupId>
   <artifactId>jstl</artifactId>
</dependency>

<!-- tomcat的支持.-->
<dependency>
   <groupId>org.apache.tomcat.embed</groupId>
   <artifactId>tomcat-embed-jasper</artifactId>
   <!-- 注掉后，可以用main启动，否则要插件run-->
   <!--<scope>provided</scope>-->
</dependency>