GEODE-1728: Http session filter should not be applied to FORWARDS

The docs should not tell users to add apply the session filter to
FORWARD, INCLUDE, and ERROR dispatchers. It should just be the default,
REQUEST.

This closes #489

geode-docs/tools_modules/http_session_mgmt/weblogic_setting_up_the_module.html.md.erb

@@ -51,10 +51,6 @@ To modify your war or ear file manually, make the following updates:
     <filter-mapping>
         <filter-name>gemfire-session-filter</filter-name>
         <url-pattern>/*</url-pattern>
-        <dispatcher>FORWARD</dispatcher>
-        <dispatcher>INCLUDE</dispatcher>
-        <dispatcher>REQUEST</dispatcher>
-        <dispatcher>ERROR</dispatcher>
     </filter-mapping>
     <listener>
         <listener-class>org.apache.geode.modules.session.filter.SessionListener</listener-class>