Munin contributed plugins

spelling: change "licenced" to "licensed"

Even though "licenced" is proper (British English) spelling,
"spellcheck" complains about it (probably being focused on American
English).
The change should just clean up the output of the spelling linter and
should not be interpreted as a language preference....

Whitespace cleanup

• remove trailing whitespace
• remove empty lines at the end of files

Plugin runs, even if no access to list DBs.

If the user as whom "munin" connects has no rights to list existing DBs,
the plugin crashes. Even though the rest of the code is OK. Listing DBs
is only necessary in the case of auto-configuring the plugin. Not for...