first-use UX

[roadscape]

Some of the main challenges for a new user on steemit.com revolve around having no followers, none followed, no community subscriptions, and an otherwise blank profile.

With a new account, check the following cases and make improvements to ease onboarding:

• [ ] empty profile (detect empty profile; encourage user to fill out basic fields)
• [ ] empty "friends" feed / no friends (link to recommended blogs or trending)
• [ ] empty "communities" feed / no subscriptions (show recommended comms)
• [ ] empty blog (encourage first blog post or resteem)
• [ ] empty posts (encourage first post or point to IntroduceYourself community)

(parent issue: https://github.com/steemit/condenser/issues/3610)