Fixes#122
Had used multiple actions for some transitions, which would lead to brief intermediary states.
Now making a few actions much more explicit about what they route to, so there is less intermediary logic, and we can transition confidently to the correct view.
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.
Calls to `eth.sign` are now transiently persisted in memory, and displayed in a chronological stack with pending transactions (which are still persisted to disk).
This allows the user a method to sign/cancel transactions even if they miss the Chrome notification.
Improved a lot of the view routing, to avoid cases where routes would show an empty account view, or transition to the accounts list when it shouldn't.
Broke the transaction approval view into a couple components so messages and transactions could have their own templates.
