[Reviewer: Mike] Application server interface and UT

Mike,

Please can you review the application server interface and my UT infrastructure?  Since we're using Google Mock, the UT infrastructure is pretty straight-forward - see appserver_test.cpp for UTs for some dummy ASs.

Thanks,

Matt
I think we should all an app server to modify the response then return true anyway.  The use case I was thinking send_response would be used for is where the app server decides it want to redirect a request (or fork it elsewhere) on a failure - in which case it might store a response and return false initially, but later on it may choose to resurrect the stored response and send it (for example, if the redirect/refork also failed).