made it work with 5.0.0.dev again

[ZelphirKaltstahl]

In version 5.0.0.dev of the notebook Jupyter.notebook.config.loaded is not a function anymore, but a promise. By taking away the () the extension works with 5.0.0.dev again =)

[jcb91]

Actually, I think it always was a promise, and the error is just a result of me confusing load with loaded (d'oh!). Thanks for catching this @ZelphirKaltstahl