Add a ignore_unknown node-level directive, allowing to selectively ignore unknown values when running munin-limits.
Also ignore transitions from UNKNOWN to OK.
Don't bail out, just prevent the state from changing.
master: do not use -p $port if unset in ssh url

If the port part is not specified in the address url, we should not
substitute it to 22.

This enables the choice to be made in /etc/ssh/ssh_config
master: adding translucent AREA+STACK
travis: adding perl 5.18
travis: build the master branch
node/t: adding some time to the test

Perl 5.18 takes longer than previous versions
doc: Digest::SHA1 has been replaced by Digest::SHA in perl core 5.9.3
munin-update with max_processes=1 is the serial option

... while max_processes=0 does what it says - and spins with 100% cpu doing nothing.
node: added --servicedir switch to munin-node

This code is copied over from munin-node-config, that already does the same
node: untaint the service-dir args
Clean field names

Non-clean field names cause problems with drawing, e.g. when there are spaces
or dashes in the process name. This commit cleans the field name by using the
appropriate support module. For more information, see:

http://munin-monitoring.org/wiki/notes_on_datasource_names
Added documentation for 'Clean field names'
Clean procargs and procuser as well

Github user @leeclemens reported that procargs should be cleaned as well and
rightly so. I took this opportunity to clean procuser as well, since usernames
could have periods (even though people should probably avoid that, if possible).

Tested procargs with 'python example.py', this gave expected results.
Allow spaces int he mount point in the plugin 'df'
fix irqstats
Use perl instead of GNU sed; fix spelling error

* Use Perl to replace configuration variables in place instead of GNU sed to
  help some poor souls without a proper GNU installation. This solves
  ticket:1403, thanks to sthen for the report.
* Also fix my previous spelling error: substitue vs. substitute. Again thanks to sthen :)
Merge pull request #148 from mattthias/stable-2.0_fix_for_ticket_1403

Use perl instead of GNU sed; fix spelling error
Fix small typo (misspelled name)