Controller rpc tests (#2709)

* Test code for controller-handler operations:

* Heal operations
* List operation
* Switch to "testing" lib, moving away from gocheck
* Minor refactors

* Remove extra call to initGracefulShutdown

* Remove dead code in mainControl:

Dead code found by the TestControlMain() test function that always
passes.

* Add tests for control-*-main.go

cmd/controller-handlers.go

@@ -127,8 +127,8 @@ type ShutdownArgs struct {
 	// Authentication token generated by Login.
 	GenericArgs
 
-	// Should the server be restarted, call active connections are served before server
-	// is restarted.
+	// Should the server be restarted, all active connections are
+	// served before server is restarted.
 	Restart bool
 }