Add support info and project summary to README

I mainly wanted to get the contact/support info into the README.  I also injected a variation of Harvest's tagline.  It's a little more concrete than "The Harvest Stack is an open source BSD-licensed toolkit for building web applications for integrating, discovering, and reporting data".

*If* putting the support info here is a good idea, we probably also want to put it in some other READMEs that first-timers are likely to be working from, e.g. omop_harvest.  Thoughts?

Signed-off-by: Kevin Murphy <murphyke@email.chop.edu>
I am inclined to either not include a verbose description like this and simply point viewers to the website or copy the text already on the website so we aren't conveying multiple interpretations of what Harvest is.