p/df: also ignore devtmpfs

devtmpfs should be excluded by default also.

I explicitly don't exclude tmpfs as it is quite useful as metric.

Closes: D:710899
Merge branch 'fix/d/710899' into stable-2.0
Remove typo in the example rrdcached socket documentation
plugins/df_abs: fix the multiple block device

The special devices like tmpfs or none can appear multiple times,
so we need to append the mount point.

Closes: D#712793
Merge branch 'fix/d/712793' into stable-2.0
Merge pull request #116 from steveschnepp/ignore-sandbox

gitignore: ignoring output dir sandbox/

Conflicts:
	.gitignore
common: add missing keywords

In commit d2f9ce0cc14efd02cbab0ff1c736e0764104d771, a new keyword was
introduced : "global_timeout".

But it can't actually be specified in munin-node.conf.

This commit also adds "timeout" in the master and "spooldir" in the node
common: refactor the keywords to ease changes

Using one keyword per line, ordered alphabetically enables a very easy change
tracability
master: fix "graph_period hour"

The "graph_period hour" setting does not work as expected, it stays "second".

Closes: #1305
Merge branch 'fix/1305-graph-period-hour-not-working' into stable-2.0
plugins: fix uninitialized $MUNIN::VERSION

Commit 733f01b1ad48c1e59f0804318a90615429f68e77 introduced a
specific user agent for munin plugins.

But it forgot to import the Munin::Plugin package.

Closes: D:717265
Merge branch 'fix/d/717265-use-uninit-val-const' into stable-2.0

Conflicts:
	plugins/node.d/nginx_request.in
	plugins/node.d/nginx_status.in
2.0.17
Substitute some @@ vars in generate files. Debian: #665688

This is a hacky solution to this problem as it uses a list of files to
substitue the variables in instead of fixing the root cause.
Merge pull request #122 from mattthias/stable-2.0

Substitute some @@ vars in generated files. Fixes Debian Bug #665688
Merge branch 'missing-configuration-keywords' into stable-2.0
plugins/open_files: fix overrided used.warn/crit

As reported by Helmut on IRC:

    < helmut> open_files from munin mainline contains both a "print_warning used"
              and a manual awk .. print used.warning
    < helmut> that can result in used.warning to be printed twice with different
              values
node/asyncd: fix a crash case

The asyncd would die() upon failure to open a new socket to the node when
--fork was not enabled.

This commit just emits a warning, and simply try again for the next plugin.
That way only a plugin fetch will fail, not the whole asyncd process.
node/asynd: avoid wake up each second
Handled single-value .sum's gracefully.

Single-value-sums now act like an identity function
instead of outputting invalid CDEFs. Further details
are in the test file