Add a product tour introduction

[macklinu]

https://github.com/matrixxun/ProductTour

This library looks cool, and it could be fun to onboarding users to the app this way. I don't really know what it would say, but I'm throwing it out there for some feedback. 😄

/cc @crebma

[macklinu]

Still not sure about this. Would be interested in feedback on this for next year, but it might be overkill considering how the app became slightly simpler to use between 2015 and 2016 (in my opinion, especially with the removal of an entire section of the app - speakers).