Stub methods in backpack controller

I was setting this up locally and had an issue after installing dependencies and running the app:

    Error: Router#get() requires all callbacks to be functions
        at Router.route.Route.sensitive (/Users/luke/Repos/openbadges/node_modules/express/lib/router/index.js:249:11)
        at Array.forEach (native)
        at Router.route (/Users/luke/Repos/openbadges/node_modules/express/lib/router/index.js:247:13)
        at Function.methods.forEach.app.(anonymous function) [as get] (/Users/luke/Repos/openbadges/node_modules/express/lib/application.js:408:24)
        at Object.<anonymous> (/Users/luke/Repos/openbadges/app.js:107:5)
        at Module._compile (module.js:449:26)
        at Object.Module._extensions..js (module.js:467:10)
        at Module.load (module.js:356:32)
        at Function.Module._load (module.js:312:12)
        at Module.runMain (module.js:492:10)

In express 3.0.5, routes without proper functions will throw an error: [visionmedia/express/#1446](https://github.com/visionmedia/express/pull/1446), so this was happening because the backpack controller wasn't exporting methods for `details` and `deleteBadge`.

This adds in stub methods these in the backpack controller and prevents the error, allowing the app to run normally. This should also get your travis-ci badge green again.

    $ node app.js
    info: environment: development
    info: opening server on port: 8888
    info: READY PLAYER ONE