Http switches

This change will allow us to turn switches on/off in non-production environments (ie CODE) and iterate on a switched off feature (ie during development) without affecting what the rest of the team sees being displayed.
Helpful when cross-functional team members work together on a feature.

This override happens only for switches explicitly wrapped in HttpSwitch (ie HttpSwitch(AudienceScienceSwitch).isSwitchedOn instead of AudienceScienceSwitch.isSwitchedOn) and within the HTTP scope.

![](http://media0.giphy.com/media/qiGjCzdYo6Qne/giphy.gif)
All these `if`s are weird. Aren't there queryParam helpers? I think you could make this a lot cleaner if you had `queryParameter` below returning an `Option[String]` instead of just a `String` only to check if it's empty. Although I know it can be hard to avoid `if`s if you are using booleans... But there's always a way!

For example, wouldn't you be able to put them into a list and then `flatten` them?