Add Universal Analytics (bug 1018934)

~~We need to add some ability to merge settings with settings provided via the page like we currently do in webpay. That can likely be done as a separate thing though.~~ See: #73
is it really necessary to disable this kind of analytical tracking? I thought 'do not track' meant 'don't show me personalized ads'. In this case, we are merely logging events just like we would log server events. I.E. if we disable tracking here we might as well disable server logs for things like 'transaction foo started for user xyz' -- that is something we definitely don't want to disable.