Warn user when address being sent to has no transaction history

[slipo]

What current issue(s) from Trello/Github does this address?
#271

How did you solve this problem?
Check NeonDB tx history for recipient address transactions. If there are none, show warning

How did you make sure your solution works?
Check the UI sending to fresh throwaway address.

• Unit tests written?

[coveralls]

Coverage decreased (-0.6%) to 40.226% when pulling 21e56d6 on slipo:no-tx-warning into 77b14d9 on CityOfZion:dev.

[evgenyboxer]

I believe you can do something like: (taken from transactions.js)

  let message = ''

  const [err, transactions] = await asyncWrap(api.neonDB.getTransactionHistory(net, address))
  if (err) {
  	message = 'Warning: there was an error verifying the recipient address has activity in its transaction history.'
  	}
  } else if (!transactions || !transactions.length) {
      message = 'Warning: recipient address has no activity in its transaction history. Please be sure the address is correct before sending.'  	
  }

  this.setState({
  	addressChecked: true,
  	addressCheckedMessage: message
  })

This way you setState only once + use the async/await.
Also - (net: NetworkType, address: string)

[coveralls]

Coverage decreased (-0.7%) to 40.119% when pulling aa7535d on slipo:no-tx-warning into 77b14d9 on CityOfZion:dev.