fix Issue 452: 	Invalid login parameters throws Workbench Context exception
fix Issue 452: 	Invalid login parameters throws Workbench Context exception

google-code-export/forceworkbench,tectronics/forceworkbench,tectronics/forceworkbench,robbyrob42/forceworkbench,Letractively/forceworkbench,Letractively/forceworkbench,gmathrubootham/forceworkbench,ganesh-sfdc/forceworkbench,gmathrubootham/forceworkbench,ganesh-sfdc/forceworkbench,Letractively/forceworkbench,google-code-export/forceworkbench,robbyrob42/forceworkbench,google-code-export/forceworkbench,gmathrubootham/forceworkbench,gmathrubootham/forceworkbench,tectronics/forceworkbench,robbyrob42/forceworkbench,ganesh-sfdc/forceworkbench,ganesh-sfdc/forceworkbench