Allow passing options to delete

[tonnenpinguin]

In order to delete for example private images as well we need to be able to pass options to the delete function.

This PR implements this behaviour and can be used like so:

Cloudex.delete(public_id, %{resource_type: "image", type: "private"})

As returning the DeletedImage struct without feedback whether the delete was actually successful makes figuring out what's going wrong quite hard I've also added the http response to DeletedImage

[coveralls]

Coverage increased (+0.5%) to 85.616% when pulling c0b3f8f on dino-keskic:master into 2d37b91 on smeevil:master.

[smeevil]

Hi,

Sorry for the absurd long response time :/
Today I went through the open pull request but in reversed order, this resulted in a conflict.

If you like to resolve those, I'll make sure it will be merged in this time ;)

[tonnenpinguin]

Closing this in favour of #65