Set CURLOPT_URL before CURLOPT_CUSTOMREQUEST

One of my users reports this PHP warning:
"Warning: Can't set CURLOPT_CUSTOMREQUEST before CURLOPT_URL in Google/IO/Curl.php
on line 57"

Hence, this tweak.
Merge pull request #162 from DavidAnderson684/patch-3

Set CURLOPT_URL before CURLOPT_CUSTOMREQUEST