Master/Slave synchronisation works again

Underlying data works again.

scalar(...) is required as $ldapObjectInstance->get returns [] when
wantarray is true as it does in hash initialisation
Add group dialog can now set the e-mail
Check email address for a group is done

Also EditGroup perform lazy operations and save performs the whole commit

This makes M/S sync works again
Proper core attr check

This makes user modification synchronisation work
Show in a slave when the user is not a member of any group
Show group in slave as read-only
Fix wording

Thanks to cperello
Merge pull request #615 from Zentyal/ejhernandez/ms-bug

Master/Slave synchronisation fixes