Add active steps detection

[gregorylegarec]

Thanks @m4dz to have a review. (ping also @CPatchane and @misstick)

This PR add a way to detect if an onboarding step is active, i.e. it it has to appear in the onboarding flow.

To handle that, it adds an isActive(user) method to Onboarding Step class, which specifies if the step has to be active for a given user (See documentation).

This method may be overriden by config steps. See for example infos step.

Infos step

Also, it add the infos step, only active when given user don't have valid email or timezone.

Also added

• Documentation
• Tests

[nono]

@gregorylegarec coffeelint is not happy :wink:

[gregorylegarec]

@nono Oops, sorry. It's the second time that it happens to me, I will see how I could add coffeelint to the npm watch task. :)

[gregorylegarec]

@nono Should be fixed now.

[nono]

@gregorylegarec you can also remove node 0.10 and node 0.12 in travis.yml

[m4dz]

Thanks @gregorylegarec !

Just for information, we'll try to not forget to update localization keys in steps markups 😉