Some description fixes

There are many more packages to fix, this is just a start.

Rules:
 * Don't repeat the package name (not always that easy...)
 * Start with capital letter
 * Don't end with full stop
 * Don't start with "The ..." or "A ..."

I've also added descriptions to some packages and rewritten others.

pkgs/development/libraries/classads/default.nix

@@ -16,7 +16,7 @@ stdenv.mkDerivation {
   
   meta = {
     homepage = http://www.cs.wisc.edu/condor/classad/;
-    description = "The Classified Advertisements library provides a generic means for matching resources.";
+    description = "The Classified Advertisements library provides a generic means for matching resources";
     license = "Apache-2.0";
   };
 }