[FIX] website_forum: remove print
[FIX] load view from file shall not raise an exception

In --dev mode, when a view can't be loaded from the file in spite of
being referenced in field `arch_fs`, the current behavior is to raise
an exception. In most cases, developpers don't want the view to fail
so the behavior has been changed in favor of a logger warning and
a fallback to `arch_db`.
[FIX] website_mail: "save and continue" button
[IMP]website_blog: change gallery view of blog post and add option into customize menu, also implement customize grid and promote blog using sequence.