Better handle API errors during sync, etc

Will be fixed when Balance and Balance Open merge is complete.

• [x] Coinbase

• [ ] Bitfinex

• [ ] Poloniex

• [ ] Kraken

• [ ] Use common errors on all exchanges

Double check that the proper UI displays now that we've completed the merge.

Need to ensure that the reconnect UI is displayed. Also need to add more UI for specific sync errors.

Will hold off until the design spec

Done for coinbase.

Merged coinbase.

Moving this to 1.0.1 as Coinbase was the important one for 1.0

Reconnect UI is done for iOS and macOS for all platforms.

The main remaining task is standardizing API errors and displaying things like when a service is unavailable so people know why an account isn't updating.

Potentially add some kind of message area in the app to tell about server issues or when coinbase is down for example

Right now it's not clear when an exchange is showing old data (for example it's been down for hours) so we should show some kind of message when the last time it updated when there's any kind of error and what type of outage it is.