Various implementation and stability patches

This pull request contains:
 - Implementation for RopModifyRecipients request with partian x500dn
 - mapistore replica layer fixed to work again - I am still testing it
 - fixed use-after-free in EcDoRpcExt2 function
 - fix for but 967 "Provisioning user with empty DN error"
   Actually the bug is more like in Zentyal server, but this commit allow for uses like:
    openchange_newuser  --create  --enable  'kcurtis'
 - small fixes