Reduce the ACL query size and decrease potential for query buffer over-run

findAcls methods produces a query with the where clause that looks like this:

```sql
(o.object_identifier = %s AND c.class_type = %s)  OR ...
```

If the class_type is the same, then we end up with a lot of fully qualified class names, which are simply repeated.

The above query can be cut down to just:
```sql
(o.object_identifier IN (%s) AND c.class_type = %s)
```
when only one class_type is present. 

The pull request does exactly that.