Modify config with plugin directories during upgrades

[BrianKoontz]

(Reported by fishy)

Upgrades to 1.1.6.6 do not modify the action/handler/template/formatter paths to include the new plugin override directories. The immediate fix is to add the paths manually:

'action_path' => 'plugins/actions,actions'
'handler_path' => 'plugins/handlers,handlers'
'wikka_template_path' => 'plugins/templates,templates'
'wikka_formatter_path' => 'plugins/formatters,formatters'

[DarTar]

We should add a how-to (including a description of valid path separators) here:  http://docs.wikkawiki.org/InstallingPlugins

[DarTar]

Retargeting to 1.3. Code for this ticket may have already been committed to trunk, from which 1.3 will be branched. Consider backporting urgent issues to 1.2.X

[DarTar]

Retargeted to 1.2

[BrianKoontz]

(In [1408]) Syntax error fixes. Refs #860.

[BrianKoontz]

(In [1407]) Default plugin dirs prepended to existing paths during upgrades. Refs #860.

[DarTar]

Tested upgrading from 1.1.6.5 - config options are modified as expected.