[TASK] Set up external accounts module

Lists bank accounts, filterable by 'gateway' and 'consumer' accounts

Links between accounts and transactions sections

Create customer and gateway bank accounts

Send inbound transaction (deposit) to gateway
if this is a toggle interface, just do it like this:
```
var opposite = {
down: 'pull-right glyphicon glyphicon-chevron-up',
up: 'pull-right glyphicon glyphicon-chevron-down'
};

this.setState({
chevronIcon: opposite[this.state.chevronIcon.iconMap]
});
```