Variables should be cleaned up upon uninstalling

Issue Summary

When you uninstall the module, the coolaid_* database tables are dropped, but the coolaid_* variables are left in the system:

• 'coolaid_existing_help_theme_function'
• 'coolaid_name'
• 'coolaid_thickbox'

Good practice would be to clean these up too, especially since it should be possible to uninstall + re-enable to reset a module's state.

Also see hook_uninstall:

Remove any tables or variables that the module sets.