Remove UCD specific items from the intro notebook to the course web page.

[moorepants]

From #166 (comment)

[moorepants]

Extra note:

In “Tour de JupyterHub” Section, include screenshot of Jupyter tab directory. Showing the Jupyter interface may be more important that showing the UC Davis login screen, especially if this book will be used at other institutions.

[moorepants]

From #159:

Notebook 1 is sort of a mix of intro to Jupyter notebooks and intro to JupyterHub. The JupyterHub-specific stuff should maybe be moved to the course website.

A slightly more general question: can people teaching with Jupyter put together a nice intro to Jupyter without much emphasis on Python? Does this already exist? I know Lorena Barba has put together a video series for something like this. I have a feeling students won't actually have all that much trouble getting up to speed with a new UI on their own, but getting a local install running may be less straightforward depending on the OS, experience with command line, etc.