Support for lomafile.com

Tries three times to download. That's it.
Is always better to avoid using `.group` directly because if the regex match fail will result in a plugin crash. It's better to use this syntax:
```python
m = re.search(r'src="http://lomafile\.com/captchas/(?P<id>\w+)\.jpg"', self.html)
if not m:
    self.parseError('Unable to get captcha ID')
captcha_id = m.group('id')
```