services: avahi: Pass --daemonize and check for the PID file.

This makes sure the service's 'start' finishes when avahi-daemon is
ready to process requests.

* gnu/services/avahi.scm (avahi-shepherd-service): Use --daemonize
instead of --syslog and add #:pid-file.

tests: 'marionette-service-type' nows takes a <marionette-configuration>.

* gnu/tests.scm (<marionette-configuration>): New record type.
(marionette-shepherd-service): Argument now is a <marionette-configuration>.
(marionette-operating-system): Adjust accordingly.  Add #:requirements
parameter and honor it.

tests: base: Add host name resolution tests.

* gnu/tests/base.scm (run-basic-test)["host name resolution",
"host not found"]: New tests.

services: Export more service types.

* gnu/services/base.scm (syslog-service-type): Export.
(urandom-seed-service-type): Export.

services: nscd: Wait for the PID file.

* gnu/services/base.scm (nscd-shepherd-service): Pass #:pid-file.

doc: Fix typo for 'static-networking-service'.

* doc/guix.texi (Networking Services): Change #:name-services to
  #:name-servers.

gnu: Add orage.

* gnu/packages/xfce.scm (orage): New variable.

gnu: python2-orator: Rearrange inputs.

* gnu/packages/python.scm (python2-orator)[native-inputs]: Move
python2-ipaddress ...
[propagated-inputs]: to here.

gnu: python-orator: Rearrange inputs.

* gnu/packages/python.scm (python-orator)[native-inputs]: Move
python-arrow, python-blinker, python-cleo, python-fake-factory,
python-inflection, python-lazy-object-proxy, python-pyaml,
python-simplejson, python-wrapt ...
[propagated-inputs]: to here.

gnu: python2-fake-factory: Rearrange inputs.

* gnu/packages/python.scm (python2-fake-factory)[native-inputs]: Move
python2-ipaddress ...
[propagated-inputs]: to here.

gnu: python-fake-factory: Rearrange inputs.

* gnu/packages/python.scm (python-fake-factory)[native-inputs]: Move
python-dateutil-2, python-six ...
[propagated-inputs]: to here.

gnu: python-email-validator: Rearrange inputs.

* gnu/packages/python.scm (python-email-validator)[native-inputs]: Move
python-dnspython, python-idna ...
[propagated-inputs]: to here.

gnu: python-cleo: Rearrange inputs.

* gnu/packages/python.scm (python-cleo)[native-inputs]: Move
python-psutil, python-pylev ...
[propagated-inputs]: to here.

gnu: python-arrow: Rearrange inputs.

* gnu/packages/python.scm (python-arrow)[native-inputs]: Move
python-dateutil-2 ...
[propagated-inputs]: to here.

gnu: python-pykafka: Rearrange inputs.

* gnu/packages/python.scm (python-pykafka)[native-inputs]: Move
python-gevent, python-kazoo, python-tabulate ...
[propagated-inputs]: to here.

gnu: python-kazoo: Rearrange inputs.

* gnu/packages/python.scm (python-kazoo)[native-inputs]: Move
six ...
[propagated-inputs]: to here.

gnu: python-twisted: Rearrange inputs.

* gnu/packages/python.scm (python-twisted)[native-inputs]: Move
python-zope-interface ...
[propagated-inputs]: to here.

gnu: Add Go 1.4.

* gnu/local.mk: Modified file.
* gnu/packages/golang.scm: New file.

Co-authored-by: Efraim Flashner <efraim@flashner.co.il>
Co-authored-by: Andy Wingo <wingo@igalia.com>
Co-authored-by: Ludovic Courtès <ludo@gnu.org>

gnu: Add khmer.

* gnu/packages/bioinformatics.scm (khmer): New variable.
* gnu/packages/patches/khmer-use-libraries.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.

gnu: Add python-screed.

* gnu/packages/bioinformatics.scm (python-screed, python2-screed):
New variables.