Merge branch 'master' into core-updates

Conflicts:
	Makefile.am
	guix/scripts/gc.scm
	guix/scripts/package.scm
	guix/ui.scm
	tests/guix-package.sh

gnu: Add vpnc.

* gnu/packages/vpn.scm: New file.
* Makefile.am (MODULES): Add it.
* gnu/packages/patches/vpnc-script.patch: New file.
* Makefile.am (dist_patch_DATA): Add it.