No longer do our `mainnet` and `testnet` buttons set specific RPC urls. Now they set `provider.type`, which gets interpreted with code.
Currently the provider types of `mainnet` and `testnet` point to our new scalable backends, but these could be re-interpreted to use any other provider, be it etherscan, peer to peer, or otherwise.
Makes it easier for us to upgrade our infrastructure without incorporating migration logic into the program.
- When unlocking, the first account is now selected by default and displayed as the main view.
- There is now a "CHANGE ACCT" button on the detail view to show the accounts list.
- Clicking an account from the accounts list now navigates to the detail view and selects that account.
- Config/Info screen "back" buttons now fire a new action, `GO_HOME`, which is configured to navigate to the accountDetail view, putting that logic in one place.
- When locking and unlocking again, the first account is always displayed, eventually we should persist the selection.
