[FIX] web_tour: make sure tips are consumed before redirections

If a tour step action induces a direct redirection the _consume_tip
method was called while the redirection was being done. Now,
_consume_tip is always called before any redirection really begins.

Note: as the run method also has to detect redirections and do actions
according to if there is one or not, a function has been created to
implement the redirection detection.