Merged revision 1601796 from tomcat/trunk:
Provide a better error message when asynchronous operations are not supported by a filter or servlet. Patch provided by Romain Manni-Bucau. Issue was reported via dev at tomcat.a.o.


git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1601797 13f79535-47bb-0310-9956-ffa450edef68