Added pipes-csv and pipes-http
Update GNU lightning to 2.0.4
Update haskell-http-kit to version 0.5.1
Merge pull request #3159 from sol/master

Update haskell-http-kit to version 0.5.1
Merge pull request #3156 from doublec/lightning

Update GNU lightning to 2.0.4
Merge pull request #3154 from 1126/master

xmobar: update to 0.21
Merge pull request #3153 from aycanirican/pipes-work

Added pipes-csv and pipes-http packages.
go: fix build of 1.0.3
mutt: update to 1.5.23

This commit rewrites this expression quite a lot:
- it uses fetchhg instead of fetchurl now.
- it simplifies the structure of the expression
- it patches configure.ac due to missing mail paths on NixOS