Add license screen to Teaser.

[yunikkk]

Message:
'I agree to the Mapbox Terms of Service and Privacy Policy_'

Terms of Service link : https://www.mapbox.com/tos/
Privacy link : https://www.mapbox.com/privacy/

[vladzima]

Add milestone, estimation, priority and move to pipeline.

[vladzima]

Relevant?

[RingerJK]

@vladzima we might add, but need to discuss

[yunikkk]

@chezzdev do you have license in teaser on iOS?

[chezzdev]

@yunikkk yes, we do. It looks like this

There's also an "info" button that provides access to the links after accepting the terms.

The links are:
Terms of Service link : https://www.mapbox.com/tos/
Privacy link : https://www.mapbox.com/privacy/

[yunikkk]

Thanks @chezzdev!
Let's add similar screens to the Teaser for Android then (@vladzima next sprint candidate?)