Allow endpoints to be registered during run()

[tsarna]

It would be nice if the endpoint classes could be registered in the application run() method, instead of having to be provided during initialize().

Among other advantages, this would allow them to be optional based on the configuration.

[eitan101]

I intentionally tried to avoid this option in order to follow the way other bundles work, for example assets-bundle.

[bucht]

Changing this would make it a lot easier to get dropwizard's configuration into the endpoint to set properties on the session for example.

[eitan101]

I added option to addEndpoint to the bundle from the run method. You can see it here.