[COOK-2339] Make slapd.conf complete configurable with attributes

The most options of slapd.conf were transfered into attributes with default
value. All important slapd.conf configuration parts (z.B. acls, databases,
indexes ...) have direct attributes. For other options generic attribute
hashes can be used to configure slapd.conf in that way you want it without
changing the cookbook.
Limitation: Replication aspect are currently not full configurable by
attributes. This is planed for later changes/tickets.