kdepim-addons: Add package expression

This is needed in order to add location information to contacts in
KAddressbook.

Packaging was quite straightforward except that it needed
akonadi-import-wizard, which I have packaged in the previous commit.

I'm committing this directly to master without a pull request, because
nothing depends on it (for obvious reasons) and packaging was trivial
enough so that if things are not as they supposed to be it can still be
changed very easily.

Tested this using the following VM configuration, because I don't run a
Plasma desktop:

(import <nixpkgs/nixos> {
  configuration = { pkgs, ... }: {
    environment.systemPackages = with import <nixpkgs> {}; [
      kdeApplications.kaddressbook kdeApplications.kdepim-addons
    ];
    users.users.test.isNormalUser = true;
    virtualisation.diskSize = 4096;
    virtualisation.memorySize = 2048;

    services.xserver = {
      enable = true;
      inherit ((import <nixpkgs/nixos> {}).config.services.xserver) layout;
      displayManager.sddm.enable = true;
      displayManager.sddm.autoLogin.enable = true;
      displayManager.sddm.autoLogin.user = "test";
      desktopManager.default = "plasma5";
      desktopManager.plasma5.enable = true;
    };
  };
}).vm

The test I've done is using KAddressbook and check whether the location
tab is working and it does now.

Signed-off-by: aszlig <aszlig@nix.build>
Cc: @ttuegel, @vandenoever