Add some api calls of image management

I add some of api calls for the API : 

- Find/Inspect an image on docker daemon
- Pull (Create with options) an image from docker registry
- Delete an image
- List all images

Let me know what you think @ubermuda
Not sure about that. It could lead to unexpected tagging when one didn't want any tagging in the first place. Also, there's no way to just name an image without a tag anymore.

What about adding an optional `$tag` argument to the method, which could default to `latest` ?