Wallet styles copy

[andytudhope]

This PR does a few things:

1. It updates the landing page copy for the wallet and simplifies what is on offer.
2. It adds typography from convo + uses the general styles from there.
3. It adds the fingerprint image used on convo to the common components as I think we should use it across more of the aps (though not necessarily all of them)
4. It alters slightly the navbar styles to fit with those from convo

It does not attend to many of the thoughts outlined in #20 because I think we need to discuss those further and think more deeply about what to do and how to represent things once someone has created a wallet.

I do agree that we should rename the page you land on from assets to something that is still generic, but less overtly financial.

[rorysaur]

@andytudhope can you post some screenshots of how the pages look now? in the PR description

[simonkernel]

I think we wanted to have the common images directory be either common/assets/images or common/src/assets/images-- deferring to @simonkernel here but I think an assets directory goes somewhere smile

You are correct that was our initial thinking.

Having said that, I'm fine going with images for now since it's the only asset we have.

We can always move it later and it shouldn't impact the dependent apps since they're importing the common package and are not concerned about the internal organization of the commons package itself.

I'll leave it up to @andytudhope and @rorysaur to make the call :grin:

[rorysaur]

Yeah, no strong preference re: assets directory and we can always change it later. One small plus is that if it's consistently src/assets/images it might be less mental overhead.