Not following redirects

Thanks for the great project!

This pull request also fixes this issue: https://github.com/loopj/android-async-http/issues/145

Had to do it, as auto following redirects really screws up my current's app workflow.

Followed the suggestion from [this](http://stackoverflow.com/a/1354387/113507) thread, and it works perfectly (300s will trigger failures).

Cheers,
- Daniel