Allow navigation from Add API Backend wizard header

[brylie]

The Add API Backend wizard shows the steps in the header area of the template. Currently, the steps do not allow users to navigate backwards when clicking. Adding backward navigation capabilities to the steps in the header may improve usability.

[bajiat]

+1

[brylie]

This should be possible using the {{ pathForStep stepId }} helper.

[jykae]

Issue using pathForStep helper, forwarder/meteor-wizard#72

Did not work as expected.

[jykae]

Got useful link how to use Wizard with Iron Router, https://github.com/forwarder/meteor-wizard#using-routers-