Switch user DN from inum to hashed_uid to get user by key (instead of query)

[yurem]

Describe the issue

Currently we run query to get user, which under high load can produce big delay. We have to switch user DN from inum to uid. In this case we can get user directly by key.

We have now:
inum=a81f5140-aef9-4922-9152-6db08d48e295,ou=people,o=gluu
We should have:
hash_uid=dfdb08d48e295,ou=people,o=gluu

SELECT gluu_doc.*, dn
    FROM `gluu_user` AS gluu_doc
    WHERE ( ( objectClass = "gluuPerson" ) AND LOWER(uid) = "user242141" )