Fix for #4489 -- apply was using the rest terminus

Basing pervasive low-level behaviour changes on the application name isn't a
good idea, but if we're going to do it we need to remember to update the test
when we rename the application. Further, if we optimize around such low-level
tests (as we did when implementing file-streaming) we need to carry the tests
over into the new data paths.

This commit addresses both of these isues, restoring 0.25.x stand-alone file
serving by adjusting the process-name test in the indirector to recognize
"apply" as standalone (and thus not use http to fetch the files) and by adding
a branch to the file streaming code to do the same when fetching the content.

I am not certain that this change is globally correct; there may be other
related problems that will not be fixed (and may in fact be exacerbated) by
this patch.