Restructure CBOX_Frontend class so some classes can be autoloaded.

Because we want our 'CBox_GES_All_Mail' class to be autoloaded (see #30),
we need to add some logic to allow this to happen.

Create new setup_globals() method - grabs existing settings from the CBOX
admin settings page and merge it with our autoloaded classes.
Remove 'All Mail' option from CBOX settings page. See #30.

This option is now autoloaded by CBOX.  See commit e9dd0e6.
Update phpDoc in frontend-ges.php.