Add timeout option for 2i requests from Riak 1.4.1.

Note that this does not include a new test, except for checking
validation of the timeout value. I attempted to provoke the timeout
but was unable to, even for 20K objects with a timeout of 1ms.
Pass timeouts through to the transports.

Also add an option to pass the timeout through next_page() when
paginating indexes.
Ensure that the proper exception type is raised and streaming doesn't continue.
Add a test for timeouts.

This is failing on HTTP because of bugs in Riak 1.4.1's streaming
index support.
Raise an error when getting an error response in HTTP streaming.
Ensure the server config is fetched before any other requests happen.
PEP8 fixes.
Merge branch 'sdc-2i-timeout' into 2.0-stable
Bump to 2.0.2.