Sort rulesets by name in preferences.

To avoid revealing which subset of rulesets has
been visited, per https://trac.torproject.org/projects/tor/ticket/11655.

cc @cooperq 
Given that this is already an operation that takes several seconds to load is there a way we can do this sort in the same loop that we load the rulesets in? Or is the sort quick enough that this doesn't actually make a noticeable difference?