[FIX] website: make theme customization modal multi-faster
[FIX] website: make theme customization modal multi-faster

Since the recent fixes on multi website, the customization modal
is restored but is a lot slower the first time we use it (around 20sec
to save an option on my machine). This was because when we change an
option, all the others options are sent to the server to be (re-)saved
and, on the first time, the multi-website system has to duplicate them
all to make them website-specific.

Now, we only enable/disable views which are modified by the user.

ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo