Merge branch 'master' into core-updates

Conflicts:
	gnu-system.am
	gnu/packages/gstreamer.scm

Thank Pjotr.

Merge branch 'master' into core-updates

Thank Daniel.

Thank Andrei.

Thank Amirouche.

Merge branch 'master' into 'core-updates'.

Thank rekado.

Add (guix elf).

* guix/elf.scm: New file.  Taken from Guile 'master', commit 3f826e3.
* Makefile.am (MODULES): Add it.
* THANKS: Thank Andy, who wrote this module.

Thank Bruno.

doc: Improve acknowledgments.

* doc/guix.texi (Acknowledgments): Expound a bit.
* THANKS: Mention artwork; thank Felipe & Nikita.

Thank Sylvain.

Thank Philip Woods.

Thank Felipe.

Merge branch 'master' into core-updates

Thank Frederico.

Merge branch 'master' into core-updates

Thank Brandon.

Merge branch 'master' into core-updates

Update AUTHORS and THANKS.