Changes min version of jQuery

For the systems that can not yet make the move to jQuery 1.9.x,
it seems unfair to prevent them from using Aura in regards to the component.json.

Aura doesn't make heavy use of jQuery features, and it seems that the most recent feature of jQuery used in Aura are Deferreds, introduced in jQuery 1.5.

I propose to lower down the required version of jQuery down to a more reasonable version, and avoid the bleeding-edge effect for existing systems relying on an older jQuery.