Re-login when the gateway is restarted during Install Wizard

Fixes [MLHR-1585](https://malhar.atlassian.net/browse/MLHR-1585)

![gwrestartlogin](https://cloud.githubusercontent.com/assets/1390651/5109761/5e63dc48-6fc8-11e4-9bb9-0c4aa99ecb46.gif)