[IMP] product: cleaned form in create mode. Moreover generally

[IMP] product: cleaned form in create mode. Moreover generally
changing the template is not possible anymore; create a new tempalte or a new
variant instead. When creating a new product, you will always create a new
template.
Added the link to the template from the product form view.
Cleaned some code (code move).

bzr revid: tde@openerp.com-20140122170218-6j2sixoxvvbbxvhd