Unwrap hibernate proxies if returned by AclObjectidentity query

I've run into a problem that I described on the [grails-user mailing list](http://grails.1312388.n4.nabble.com/Spring-Security-ACL-plugin-amp-proxy-instances-tt4628633.html) where I sometimes have proxies returned in the HQL query created in GormAclLookupStrategy.lookupObjectIdentities. This ends up resulting in a problem in GormAclLookupStrategy.findAcls because the map is seeded with the proxy classes, but then when looping over the entries it tries to left shift onto an uninitialized key because the entry.aclObjectIdentity is NOT a proxy.

I hope that makes sense. Please let me know if this is a pull request that you might consider or if you know of an alternate solution to my problem.