added ability to use show commands on objects that are not the current p...

...lot

@bryevdv @LilaHickey @kdodia 

added a function so we could show crossfilter in the notebook (and debug why the css is not looking great)


Just a note... the `load_notebook(force=True)` is something we probably have to keep in this example because it let us test the nbconversion of `ipynb` to html, and it is also informative for people looking into the low level API...