Supertest delete method is del, not delete

[alavers]

Superagent uses 'del' instead of 'delete' to avoid conflicting with the javascript reserved word. Supertest-as-promised doesn't appear to account for this, the following attempt will fail:

request(app)
      .del("/kittens/123")

I've opened #3 which makes the code above work properly.

[benesch]

Comments in #3.

[benesch]

Fixed!