Add package: snapper

Snapper is a tool for Linux filesystem snapshot management, developed for OpenSuSE.
Add python package: snapper-gui

Graphical frontend for snapper.
Not tested, yet.
Use Nix default version of boost library.
Disable tests for snapper-gui
Fix #4236
Merge pull request #4226 from ts468/snapper

Add package: snapper
coq_HEAD: update to latest Git HEAD
openafs: fix on kernel 3.16 with upstream patches
dotconf: update from 1.0.13 to 1.3 and adopt it
darcs: link this binary statically to avoid run-time dependencies on GHC and friends
git-annex: link this binary statically to improve start-up times and to get rid of some run-time dependencies

https://github.com/NixOS/nixpkgs/issues/4239
haskell-jwt: re-generate with cabal2nix