Make mudskipper not a singleton.

- This means that when hapi supports multiple instances of the same plugin mudskipper will work.
- This also allows you to access Mudskipper directly, so that you can instantiate the module multiple times independently (not as a plugin) without hapi complaining.

example usage standalone in another hapi plugin:

```javascript
var Mudskipper = require('mudskipper');

exports.register = function (plugin, options, next) {
    plugin.loader(require);
    var mudskipper = new Mudskipper({
        makeRoutes: plugin.route.bind(plugin)
    });

    mudskipper.buildRoutes({
        resources: {
            users: {
                index: function (request, reply) {
                    reply([{ name: 'plugin1' }]);
                }
            }
        }
    }, next);
};
```