[ADD] CDN support for website
[FIX] product: remove empty from state field selection

In order to avoid having twice "empty" in the web client. There is always an empty option in selection field in the web client. When the selection field is required, you have to select it, and it is not required, you can set False as selection value
[FIX] website_quote: onboarding tip
[IMP] Accounting typos fixes in tips
[IMP] Quotation form view fields moved
[IMP] change webclient structure: remove table

This is a small change if measured in lines of code, but is a large
change: it removes the table structure from the web client and use divs
instead.  It will likely break a lot of things (some css selectors
will not work), but it should simplify our lives in the future:
closer to being responsive, easier layout computations for the browsers
(and hopefully less discrepencies between the results), simpler html, ...
[FIX] fix display issue in IE in kanbans

vertical text in folded kanban groups did not have a correct
orientation in IE.

Also, stupid sass compiler insists on normalizing color codes. No idea
why
[FIX] properly destroy client widgets (web client)

The new action manager only destroyed viewmanager widgets instead of
any old widget.  It now checks for the widget class.

Also, minor improvement to clear_widgets: vms used to stand for
view_managers, but it can destroy any widget.
[FIX] hide 'add to dashboard' in mail menu

add to dashboard does not work with messaging client actions. So,
better to hide it than to have crashes.
[FIX] correctly display check marks in measures (graph)
[FIX] various css fixes (advanced search)

* dashboard did not display properly kanban in ie
* kanban did not extend to the bottom of the available screen
* custom filters did not display anything different when they were
public (not private)
* some small css problems
[FIX] fix button looks in module install view

The 'install' and 'installed' buttons are supposed to look different,
and to show the 'disabled' look on already installed modules.
[FIX] add tooltip to some buttons (graph view)
[FIX] css fix in left menu (web client)