fix(ad_group_mu_ucn): Check uniqueness of ad group name
fix(ad_group_mu_ucn): Check uniqueness of ad group name

 * AD group name must be unique for all groups in tree structure. If
not, script must end without continuing and wait till administrator
fix the situation manually.

CESNET/perun-services,zlamalp/perun-services,CESNET/perun-services,zlamalp/perun-services,CESNET/perun-services,CESNET/perun-services,zlamalp/perun-services,zlamalp/perun-services