Piwik not found error & suggested plugin display

Fixed cleanupPiwikDB "Class Piwik not found", typos, unneeded comment calls, wrong display of suggested plugins
Suggested plugin display

return suggested Plugins in enableSuggestedPlugins() to display them correctly e.g. in ext_update.php
Merge pull request #13 from sgrossberndt/master

Piwik not found error & suggested plugin display