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/applications/networking/ids/bro/default.nix

@@ -15,7 +15,7 @@ stdenv.mkDerivation rec {
   enableParallelBuilding = true;
   
   meta = {
-    description = "Bro is a powerful network analysis framework that is much different from the typical IDS you may know.";
+    description = "Powerful network analysis framework that is much different from the typical IDS you may know";
     homepage = http://www.bro.org/;
     license = "BSD";
   };