Trove API create/update calls cannot have empty host strings

[Riddhi]

The trove api create/update calls should throw a BadRequest in case of empty host strings.

For example:
In case of modify user attributes API,
if the client sends an empty host attribute, the API accepts it; however, the API will no longer find the user on the next requests.

Send an update containing an empty host:

$ curl \
    --request PUT "https://dfw.databases.api.rackspacecloud.com/v1.0/708784/instances/94db0f63-2423-454a-bb22-91dc444b60ef/users/gandalf" \
    --data "{ \"user\" : { \"host\": \"\" } }" \
    --header "Content-Type: application/json" \
    --header "X-Auth-Token: 7e08297922a245748b074d6142956709" \
    --insecure \
    --write-out "http_code=%{http_code}"

It returns 202.

If you try to update it again or delete the user, it returns:

{"itemNotFound": {"message": "User gandalf cannot be found on the instance.", "code": 404}}

This triggers the need to explicitly throw a BadRequest in case a empty host string is specified.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/43005

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/43005
Committed: http://github.com/openstack/trove/commit/926a5ea721f9b155ce3d074694075b742d8c3306
Submitter: Jenkins
Branch: master

commit 926a5ea721f9b155ce3d074694075b742d8c3306
Author: Riddhi Shah <email address hidden>
Date: Tue Aug 20 16:41:18 2013 -0500

    Modify User Attributes API - Fix

    This fix does not allow empty host strings in the update user call.
    Besides, it also enusres that database access is not lost during an update of the host attribute

    Change-Id: I57b7733c264d2bcd70dfea95f85aae68553c4dff
    Fixes: bug #1214166
    Fixes: bug #1214555