Replace txagentwithsocks in httpt template
Finish adding support for using txsocksx in HTTP templat in HTTP templat in HTTP templat in HTTP template

* Make sure we are using the TrueHeaders and in SOCKSAgent and Agent
Fix unittest for true headers..
Add support for using txsocksx inside of oonibclient.
Start adding support for using txsocksx inside of oonibclient.

There is some badness happening because we use the httpo (HTTP over Tor Hidden
Service) as the scheme name.
Use our TrueHeaders version of the SOCKS5Agent in oonibclient
str().replace() returns a copy and does not modify in place.
Merge pull request #208 from TheTorProject/feature/use_txsocksx

Feature/use txsocksx