Quote from the Spring reference doc:
Upon initialization of a DispatcherServlet, Spring MVC looks for a file named [servlet-name]-servlet.xml in the WEB-INF directory of your web application and creates the beans defined there...
Your servlet is called spring-dispatcher, so it looks for /WEB-INF/spring-dispatcher-servlet.xml. You need to have this servlet configuration, and define web related beans in there (like controllers, view resolvers, etc). See the linked documentation for clarification on the relation of servlet contexts to the global application context (which is the app-config.xml in your case).
One more thing, if you don't like the naming convention of the servlet config xml, you can specify your config explicitly:
<servlet>
<servlet-name>spring-dispatcher</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/spring/appServlet/servlet-context.xml</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>