Add --output-format command line option

Right now we have normal, terse, and json output. Lets add a parameter
that controls how to output results, instead of having options for
both terse and json outputs. If we are going to add a 4th output
type in the future, it's only going to get more messy.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/README b/README
index a135017..535b077 100644
--- a/README
+++ b/README
@@ -125,8 +125,9 @@
 	--latency-log		Generate per-job latency logs
 	--bandwidth-log		Generate per-job bandwidth logs
 	--minimal		Minimal (terse) output
-	--version		Print version info and exit
+	--output-format=type	Output format (terse,json,normal)
 	--terse-version=type	Terse version output format (default 3, or 2 or 4).
+	--version		Print version info and exit
 	--help			Print this page
 	--cmdhelp=cmd		Print command help, "all" for all of them
 	--enghelp=engine	Print ioengine help, or list available ioengines