Update urllib3 to 59de03e6163c6928dc01832ed6e48e9f6c34c795.

This update includes two fixes:

* https://github.com/shazow/urllib3/issues/149
* https://github.com/shazow/urllib3/issues/174
Merge pull request #1332 from bboe/urllib3

Update urllib3 to 59de03e6163c6928dc01832ed6e48e9f6c34c795.