refactor enableViewRouting and app enableDeviceHelpers

I ran into the same issue as #20

I did some digging and found that device was attaching enableViewRouting and enableDeviceHelpers to the local version of express in its own node_modules, which doesn't affect express further up in the root node_modules or global node_modules since they are stored differently in the require.cache.

This refactor solves that issue by passing the reference to the individual app instead of affecting all apps.This approach also benefits cases where you have more than one express applications listening on different ports in the same script (ex SSL). Since the previous method modified the prototype, it would apply the extra middleware to every instance of app. This also prevents any possible breaking changes from express since it doesn't modify the app's prototype.