Email hooks on more specific actions

As I'm trying to adopt my existing email sending code to the new email feature, I'm trying to understand how that works.
As a side-effect I have some suggestions how you could hook your stuff to more specific actions then "init" hopefully making Jigoshop more secure.

Note: these changes are not tested, I've just verified them against WordPress code.

Also I've found two identical functions: `jigoshop_upgrade_1_13_3` and `jigoshop_create_emails`.
I can see (and I was also complaining about this before, if you remember ;)) that these two serve different purposes, I'm just wondering if `jigoshop_upgrade_1_13_3` could just simply call `jigoshop_create_emails` and there would be no code duplication. Of course the duplicated code doesn't harm me in any way, I'm just sayin'...