Changes from Version 1 to 2
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@AUTHOR: Ignacio Vázquez - <elpepe.uy at gmail.com>

- 	Tab panel type: system -> plugin
	When disable this plugins, the tab panel did not disappear from UI. So when accessing here it trows 'Invalid Controller'.
	Changing from 'system' to plugin, the core checks if the plugin is intalled/activated before render.

- 	Manual Upgrade instructions:
	UPDATE fo_tab_panels SET type = 'plugin' WHERE id='mails-panel'
