[CLEAN] website_event: migrate models to the new API + some code cleaning.

Updated some code in website_event_track, inheritance with new API.

Controllers need a major cleaning, but, hey, they are too creepy.
[IMP] web: nodeValue is deprecated
[CLEAN] event_sale: lint / cleaned module, migrated event models to the new API.
[IMP] Event: Split Tickets
Attendees are created on SO confirm.
Attendees are directly created for FREE registrations and
Attendees are created and SO are linked to the paid tickets.
Improved code to make (5 attendees lines, 2 SO lines) when 3 vip tickets and 2 standard tickets are bought.

This commit fullfills the following Goals:

Goal 1 : When only website_event is installed, free registration should be possible from website.
Goal 2 : When only event and website_event are installed, badge report should be print for free registrations.
Goal 3 : When website_event_sale is installed, at that time on confirming the sale order, the subscription line are splited per attendees.
Goal 4 : Added code for attendees registrations through SO. Now from SO also the attendee's details for the event can be filled same as from website