Session = function (options) {
        this.id = null;
        this.notebook_model = {
            path: options.notebook_path
        };
        this.kernel_model = {
            id: null,
            name: options.kernel_name
        };

        this.base_url = options.base_url;
        this.ws_url = options.ws_url;
        this.read_only = options.read_only;
        this.session_service_url = utils.url_join_encode(this.base_url, 'api/sessions');
        this.session_url = null;

        this.notebook = options.notebook;
        this.kernel = null;
        this.events = options.notebook.events;

        this.bind_events();
    }
Session object for accessing the session REST api. The session
should be used to start kernels and then shut them down -- for
all other operations, the kernel object should be used.

Options should include:
 - notebook_path: the path (not including name) to the notebook
 - kernel_name: the type of kernel (e.g. python3)
 - base_url: the root url of the notebook server
 - ws_url: the url to access websockets
 - notebook: Notebook object

@class Session
@param {Object} options