Migration of website module to new API.
The tricky phase is ir_http.py : we need to use `request.env`
only when the authenfication phase is done. Normally by
calling `super` of `_dispatch` method, but website module
required it to be done before. This is important since
`env`is a lazy property of `request` object.
Some hack were kept since this commit is a migration ('RequestUID'
in ir.http, ...)
Some docstrings were added.
xmo-odoo