OO-1282: rewrite the reload method to accept nothing as a result without error ( and connection set to rollback )

OO-1276: course administrator and course tutor have access to the results of the course participants

OO-1278: the change executor must be the first in the chain of login interceptors (it don't need any GUI)

no-jira: add external reference and id of courses in the list of membership of users in the user administration

no-jira: fix last step of bulk user import if the e-mail are mandatory and the e-mail step is disabled

no-jira: fix last step of bulk user import if the e-mail are mandatory and the e-mail step is disabled

OO-1273: fix open/close of pages in CP, fix open CP course node with sub course nodes and only one page