implement stop and start app buttons in UI

- the buttons are implemented and wired to methods
in app.controller
- a service needs to be implemented
- need logic for determining if the app is currently
runnig to disable or enable the buttons

- tweaks to polling and state after error and refresh

- convert timer to a constant value

- remove console.log statement
Merge pull request #391 from strongloop/feature/add-stop-start-buttons

implement stop and start app buttons in UI