Let statemachine honor approvements.

The inventory bulk fetch is not thread-safe, so the it doesn't start
right away, causing the approvement not to be honored upon return from
post_approved (formerly post_nb).

This patch renames wantsMoreHTTPReqestsFor to approveHTTPRequestFor,
and has it return NULL or a AIPerService::Approvement object.
The latter is now passed to the CurlEasyHandle object instead of just a
boolean mQueueIfTooMuchBandwidthUsage, and then the Approvement is
honored by the state machine right after the request is actually added
to the command queue.

This should avoid a flood of inventory requests in the case
approveHTTPRequestFor is called multiple times before the main thread
adds the requests to the command queue. I don't think that actually ever
happens, but I added debug code (to find some problem) that is so damn
strictly checking everything that I need to be this precise in order to
do that testing.

indra/llmessage/aicurlperservice.cpp

@@ -366,3 +366,9 @@ void AIPerService::Approvement::honored(void)
   }
 }
 
+void AIPerService::Approvement::not_honored(void)
+{
+  honored();
+  llwarns << "Approvement for has not been honored." << llendl;
+}
+