[FIX] update the search tests

The search tests are totally outdated since the search view rewrite. This commit update them to the new search view.
[FIX] catch possible exception in search.js

The search view tries to evaluate the category of a filter in order
to put it in the filters or in the group by sub menu.  The pyeval.eval
function could throw an exception, which is not cool if it crashes the
client.  This fix make sure that the exception is caught.
[FIX] update tests in search view
[FIX] remove search.invisible tests

The search view architecture allowed an 'invisible' attribute in fields.  These fields were ignored for the autocompletion and did not appear in the interface.  The goal was to allow default parameters to create facets, without displaying the field in the interface.  Since that functionality is not used and the new search view does not support it right now, the tests can be removed.
[FIX] put the scrollbar back in web/tests

for some reason, the web tests interface loads base.css, in which the .openerp is overflow:hidden, which is not fun in the tests.

The correct fix is actually to remove base.css from the tests, but the way I did it had some problems. So, this is a simple workaround that can be safely removed if base.css is removed from the view.
[FIX] fix a crash in sub kanban views

sub kanban views is sometimes initialized without a $buttons attribute in options.  In that case, it should just ignore it.