The kanban view uses a template which comes from the server, already
translated. Before this commit, it tried to retranslate again the
template in qweb.js, which may be a problem (in addition to the useless
work): if some english string A is translated in B (french), but B is
also a valid english string which is translated into C in french, then
we will have a wrong result.
In this commit, we simply add a flag to disable the translation process, which
should also slightly improve the kanban view rendering performance.