Add a Binder module to the homepage

[palewire]

Per the discussion in #529, the /binder page should be represented on the homepage. How so is open to debate. One idea would be mimic the module style now used for JupyterLab and Jupyter Notebook.

[jayeshsingh9767]

@palewire I would like to take this up, just wondering where will I get the Promotional image and Content for binder ?

[palewire]

Great question. I don't know! I suspect one of the project leaders could help you here.

[manics]

Would the aim of this page be to promote mybinder.org (probably best to hold off till we get a bit more funding/capacity) or BinderHub?