Configure gnupg to use pinentry by default.

This makes gnupg much more usable out of the box.
Remove obsolete patch.
Remove use* options and let the user set optional dependies to null if
they don't want to use them.
Apply recent changes from gnupg/default.nix to gnupg/git.nix

gnupg/git.nix doesn't build, but it didn't build before either.
Add roconnor to GnuPG maintainers.
Remove unmaintained gnupg2_1.
Comment on optional dependencies for Gnupg.
pypyPackages.sqlalchemy_imageattach: disable tests on pypy
strongswan: Properly handle sysconfdir, build swanctl
add symlink to chromium-browser for xdg-open to work as expected
Update OpenAFS client to version 1.6.9
xfsprogs: 3.1.11 -> 3.2.1
xfsprogs: Actually fix library rpath
kernel: 3.10.54 -> 3.10.55
kernel: 3.14.18 -> 3.14.19
kernel: 3.16.2 -> 3.16.3
nginx: 1.6.1 -> 1.6.2

Additionally, update all extensions and convert them to fetchFromGitHub
xfsprogs: Add missing patch
Merge pull request #4120 from NixOS/gnupg

Add pinentry optional dependency for gnupg.

Delete gnupg2_1.
Drop the jakarta name from BCEL and update its version.

Closes #4180.

Signed-off-by: Mateusz Kowalczyk <fuuzetsu@fuuzetsu.co.uk>