Added postgresql

Added a postgresql to system, also tryed to install Java with
dependencies of JavaFX but it doesn`t work.

nixos/hosts/usconfig/models/postgresql.nix

@@ -0,0 +1,10 @@
+{config, pkgs, ... }:{
+  config.services.postgresql = {
+    enable = true;
+    ensureDatabases = [ "mydatabase" ];
+    authentication = pkgs.lib.mkOverride 10 ''
+      #type database  DBuser  auth-method
+      local all       all     trust
+    '';
+  };
+}