Moving data and adding skip option

Due to changes in Hapi, I am moving the data storage from request.session to request.yar. This will be more future proof, but will necessitate some code changes for those upgrading from v5 or earlier. I apologize for the inconvenience, but that is why this is a major version change.

This also includes a new route level configuration option that allows you to disable yar on a route by route basis. This let's you avoid any processing from yar on routes that don't need sessions, making your application more responsive. See the docs for more info.