[jsoncontroller] deprecate the now unused js_set_cookie (closes #1944810)

[repo] ensure we don't restart a task while the repo is shutting down (closes #1942736) we need a safety belt in cw itself again looping task which use 'try / except' or doesn't need to access the db (which will trigger ShuttingDown exception)

[warnings] explicitly ask to show DeprecationWarning in debug mode (closes #1942760) as python 2.7 don't show DeprecationWarning by default

[testlib] make self.view() return raw output if no validator is used This will make it possible to parse and test view's output even if no validator is associated to the view's content type.