content suggestions for front page

[mmckerns]

*) Front page is clean, eye-catching, but obviously a stub. That's ok, minimal is good as long as it does it's job.

*) It should define the difference between diffpy and diffpy-cmi more clearly. It's two projects? Does the first paragraph describe diffpy first, then diffpy-cmi next? it's confusing. Should state what each project is, and what the goals are up front… or have one page each that does that.