invalid memory address or nil pointer dereference

Hey!

I ran the following command:
```
$ ./dirsearch -url https://localhost -wordlist /tmp/dotdotpwn.txt
```

Wordlist available @ https://raw.githubusercontent.com/foospidy/payloads/master/other/traversal/dotdotpwn.txt

Got:

```
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x38 pc=0x1221602]

goroutine 36 [running]:
main.DoRequest(0xc00100a7a0, 0x17, 0x1289001, 0xc001112fc0)
/Users/Shaked/.go/src/github.com/evilsocket/dirsearch/cmd/dirsearch/main.go:65 +0x242
github.com/evilsocket/dirsearch/vendor/github.com/evilsocket/brutemachine.(*Machine).inputConsumer(0xc00012c000)
/Users/Shaked/.go/src/github.com/evilsocket/dirsearch/vendor/github.com/evilsocket/brutemachine/machine.go:78 +0xa7
created by github.com/evilsocket/dirsearch/vendor/github.com/evilsocket/brutemachine.(*Machine).Start
/Users/Shaked/.go/src/github.com/evilsocket/dirsearch/vendor/github.com/evilsocket/brutemachine/machine.go:97 +0x55
```

Any ideas?