include basic description paragraphs for F-Droid and server in README
include basic description paragraphs for F-Droid and server in README

Having these basic descriptions in the README provides a quick way to find
out what F-Droid and fdroidserver are.  Plus it will show up on the
gitorious git repo, and will automatically be included in the Python
packaging, where it will be pushed to pypi and other places.

f-droid/fdroidserver,OneEducation/AppUniverse_Server,pfalcon/fdroidserver,pfalcon/fdroidserver,fantastico/fdroidserver,matlink/fdroidserver,f-droid/fdroid-server,fantastico/fdroidserver,OneEducation/AppUniverse_Server,matlink/fdroidserver,f-droid/fdroid-server,f-droid/fdroidserver,f-droid/fdroidserver,OneEducation/AppUniverse_Server,OneEducation/AppUniverse_Server,fantastico/fdroidserver,fdroidtravis/fdroidserver,fdroidtravis/fdroidserver,f-droid/fdroid-server,pfalcon/fdroidserver,fdroidtravis/fdroidserver,f-droid/fdroid-server,matlink/fdroidserver,f-droid/fdroid-server,pfalcon/fdroidserver,OneEducation/AppUniverse_Server,matlink/fdroidserver,f-droid/fdroidserver,fdroidtravis/fdroidserver,fantastico/fdroidserver,f-droid/fdroidserver,pfalcon/fdroidserver,fantastico/fdroidserver,matlink/fdroidserver