Create Plugin Problems Page

[aljawaid]

Create a page for the plugin side menu as Plugin Problems

Add content which shows the common problems which users face with badly structured or outdated plugins.

Areas to cover:

• Further Help
  • link to plugin section of forum
  • link to support page of KanboardSupport showing technical info (if installed)
  • link to kanboard instance about page
• Plugin Uninstalling
• mention manual way to uninstall plugin (delete folder)
• Plugins with Database Changes (highlighted through the new Plugin Manager)
  • Mention the need to cross-check the database for extra tables (also plugin schema table thanks @alfredbuehler )
  • Add example command to delete tables from Mysql database