Design a user interface for Salmon

We need to start thinking about Salmon's user interface. In an ideal world, we would build it into Tor Browser and make it so that users will never be exposed to bridge lines at all.

For now, Salmon supports the following user-facing actions:

1. Sign up by being invited by somebody else.
2. Sign up by registering (we don't have a good plan for that yet).
3. Receive a bridge.
4. Invite somebody else to Salmon.
5. (Optional) Take a look at your reputation and invite graph.

Tor Browser could talk to our Salmon backend (which will be part of rdsys) using a domain-fronted API, similar to how moat works.

Copying @cohosh, @antonela, @gaba, @arma, and @sysrqb.