Fix bug that prevented configuring timeout setting
Make 3 minor internal improvements.

 * Use "or" rather than "is None" in a tenerary operator to choose
    bewteen the argument timeout or the default. Using "is None"
    implied that 0 is a legit value for the timeout (it is not).
    Additionally using "or" is the generally used way in PRAW of
    determining between a variable and default.
 * Replace magic number 200 with request.ok just like 7f0b6e0.
 * Enforce alphabetical ordering of _get_section methods in Redditor.
Add notes about clients voting.

Note is taken directly from API documentation.
http://www.reddit.com/dev/api#POST_api_vote
Use new is_lazy_loaded attr instead of _populated

This will enable users to see whether an object has been lazy loaded
without using a private attribute.
Add Lazy loading page to documentation.
Switch to using "Nature" sphinx theme.

It's prettier. Has clearer headlines separating the content. It
includes a search for searching PRAW rather than RTD. The sidebar
also wraps lines, whereas in default it cuts off lines that are
too long.