'Add a user to an issue\'s watchers list.
:param issue: ID or key of the issue affected
:param watcher: username of the user to add to the watchers list'

@translate_resource_args
def add_watcher(self, issue, watcher):

    url = self._get_url(((u'issue/' + str(issue)) + u'/watchers'))
    self._session.post(url, data=json.dumps(watcher))
