Returns the public URL in response.

After a succesful upload, the server returns the public URL to the image
in the response.
Adds public_url to the config.
Fixes public URL response.
Fixes public url.
Removes restriction on filenames.

The only restriction now is there there be no '/' and a limit on extensions.
Adds a default directory when no directory is given.
Adds a spec for using the default directory.
Handles duplicate file names by appending numbers.
Returns the correct filename.
Removes directory from request check.
Handles non-XHR requests.
Removes unneeded code.
Fixes specs.
Fixes writing content to the response.
Refactors to use local/cloudinary adapters.
Fixes namespacing issues and filename issues.
Use _ instead of ().

Because the URL is encoded.
Removes unneeded code.
Removes rescue for all errors.
Updates snapimage_generate_config to handle the different adapters.
Updates the README file.