stumpwm: update and refactoring

This commit updates the stumpwm to version 0.9.8. Futhermore, it
refactors the expression quite a lot:

* stumpwm has been moved from lisp modules to window-managers.
* stumpwm has been added to the window managers NixOS knows about, this
  enables the user to add stumpwm as a default window manager in his
  NixOS configuration like with Xmonad or i3.
* the package has been split into stumpwm and stumpwmContrib. This is
  due to the fact that development of stumpwm and its extension modules
  has been split into two repositories. As of today, the release is the
  last one before this split. This split into two packages only reflect
  those upcoming upstream changes already.

It is planned to make the addition of the extension modules voluntarily,
like with Xmonads option "enableContribAndExtras". Furthermore it might
be possible to add an option to compile stumpwm with clisp instead of
sbcl.
stumpwm: removed from lisp-packages.
logstash service improvements

* add logstash-contrib plugins package
* add additional options to the logstash service
udisks: update from 1.0.4 to 1.0.5
Add claws-mail and libetpan.

Adds Nix expressions for claws-mail (http://www.claws-mail.org) and a
dependency that is not already in the tree, libetpan
(http://www.etpan.org/libetpan.html).

The Claws expression has flags for toggling the build of various plugins.
Added the grassroots DICOM library.
Added the dlib machine learning library.
Fixed the mirror:// download link for GDCM.
proot: remove self.stdenv.lib
Merge remote-tracking branch 'nixos/master' into proot

Conflicts:
	pkgs/tools/system/proot/default.nix
new package: svg2tikz
Add license for svg2tikz
Removed akunambol

It is not maintained anymore, and is not compatible with kde 4.14.
Made kde 4.14 the default kde
Removed kde 4.12
add patches for openafs-client on kerel 3.17
Add a jobset for a "nixos-small" channel

This channel only builds a small subset of Nixpkgs, mostly suitable
for servers. Since the channel update doesn't require thousands of
packages to be built first, it should provide much faster turnaround
in case of security updates.

(cherry picked from commit 2c7acc6731ad4b05b1bbc3e632cdfcad4560ac22)
Remove missing attribute

(cherry picked from commit f963f57b6230679c6194889a05fcb7741883af70)
Add an entire NixOS build to the channel

This causes some cruft to be uploaded (such as unit files) but it
ensures that every package used by the base system ends up in the
channel, not just environment.systemPackages.

(cherry picked from commit 4dfca8e14a5d1c2e62bb5ad267163a7a32ef872f)
Add some more stuff to the small channel

(cherry picked from commit 8cf528174465c195dc9807075ef889d91994f018)