Use effective_url instead of url for logging

Whenever I look at logs from ethon, I get something like 
```performed EASY url= response_code=200 return_code=ok total_time=0.28435``` . 

I'm on OSX, ethon version 0.7.

This seems to fix it so that I can see the url in my logs ```EASY effective_url=http://www.example.com response_code=200 return_code=ok total_time=0.28435```- although I don't know whether there's a better solution.