Faild created a search thread when login
Hi!
Ubuntu 16.04

When trying to login using 
```curl  -w "\n" -X POST http://127.0.0.1:1984/login -d '{"address": "A2VTvE8bC9APsWFn3mQzgW8Xfcy2SP2CRUArD6ZtthNaWDuuvyhtBcZ8WDuYMRt1HhcnNQvpXVUavEiZ9waTbyBhP6RM8TV", "view_key": "041a241325326f9d86519b714a9b7f78b29111551757eeb6334d39c21f8b7400"}'```

Get this error.  
```
osboxes@osboxes:~/openmonero/build$ sudo ./openmonero
Blockchain path: /home/osboxes/.bitmonero/lmdb
Start the service at http://127.0.0.1:1984
Check block height: 175586 no of mempool txs: 0
Check block height: 175686 no of mempool txs: 0
Error getting address: A2qMy9i5Dgt1dFzb6kB9rsffDEUisW69HWTRuEM8LiB13YKzFeR4YrFVxsA9cZeEF9F1hgGWb5JT7UAEhHKwKR1LJ13aYTT
Cant parse string address: A2qMy9i5Dgt1dFzb6kB9rsffDEUisW69HWTRuEM8LiB13YKzFeR4YrFVxsA9cZeEF9F1hgGWb5JT7UAEhHKwKR1LJ13aYTT
Faild created a search thread 
Check block height: 175786 no of mempool txs: 0
```

By the way, get_random_outs, get version api works fine
