If buddy is on neither Allow nor Block list, then add to Allow list.
At some point, we should figure out if the NetworkInfo really is used
for this sort of thing.
/** @page gtkaccount-signals GtkAccount Signals
@signals
@signal account-modified
@endsignals
@see gtkaccount.h
<hr>
@signaldef account-modified
@signalproto
void (*account-modified)(PurpleAccount *account);
@endsignalproto
@signaldesc
Emitted when the settings for an account have been changed and saved.
@param account The account that has been modified.