Move all output through StatusOutput

Write log output through StatusOutput so that the status implementation
can synchronize it with its own output.

Test: status_test.go
Change-Id: I917bdeeea4759a12b6b4aa6d6d86ee18a2771723
diff --git a/ui/status/status.go b/ui/status/status.go
index 46ec72e..3d8cd7a 100644
--- a/ui/status/status.go
+++ b/ui/status/status.go
@@ -173,6 +173,9 @@
 	// Flush is called when your outputs should be flushed / closed. No
 	// output is expected after this call.
 	Flush()
+
+	// Write lets StatusOutput implement io.Writer
+	Write(p []byte) (n int, err error)
 }
 
 // Status is the multiplexer / accumulator between ToolStatus instances (via