/etc/rpm*.conf back to /etc/sysconfig/

It's the right thing to do. This is not a config file, it's
a short file with simple envariable settings, intended for
use by systemd via EnvironmentFile. And, on RHEL7:

  # grep -R EnvironmentFile /usr/lib/systemd/system/|wc -l
  37
  # grep -R EnvironmentFile /usr/lib/systemd/system/|grep -v /sysconfig/
  36

That is: EnvironmentFile=/etc/sysconfig/<something> appears
to be a strong RHEL convention. We should abide by it.
KRB5CCNAME: take advantage of systemd env

systemd provides EnvironmentFile=<path>, and we're already
using that for pointing to our config file. Take advantage
of that feature to also define KRB5CCNAME. This removes
some complexity from the code, and also eliminates a
potentially thread-unsafe use of putenv().
use systemd instances.

We may need to run multiple instances of a message bus
listener, with different configs for different message
types or brokers. This appears to be the systemd-sanctioned
way to do so. See

    http://0pointer.de/blog/projects/instances.html

Usage diff:

  - systemctl start rpm-ostree-toolbox-build-monitor.service
  +   "   "    "  "  "   "  "   "  "   "  " -monitor@foo.service

...where foo is an instance name. Each instance must have
a corresponding /etc/sysconfig/rpm-ostree-toolbox-foo file.
Restart services on failure.

Failures are common with QPID: network hiccups, planned
outages, gremlins.

Much as I wanted to leave this as a site policy decision,
there doesn't seem to be a simple systemctl-ish way to do so.
See systemd.service(5) for restart directive, and perhaps
rhbz#756787 for hints on how to use /etc/systemd for
local overrides.

On kinit.service, set RemainAfterExit=yes. This serves as
a flag for build-monitor.service
Whew! Fix systemd dependencies.

First: use both After= and Requires=. They're different.

Second: make -build.service depend on kinit timer *and* service.
This starts the timer (which doesn't seem to check or care about
exit status of the kinit script) and also runs the service.