Add API in the auth provider to resolve user names from the CLI.

Sample usage:
```
headers = { 
    'Authorization': 'Bearer {0}'.format(service_auth_token)
}
data = [
    ('names', ('test1', 'notthere', 'user1')) # list of user names to resolve
]
info_url = 'http://localhost:8000/clients/info/'
request = urllib2.Request(info_url, urllib.urlencode(data, True), headers)
try:
    response = urllib2.urlopen(request)
    result = json.load(response)
    status_code = result['code'] if 'code' in result else 500
    if status_code == 200:
        for user in result['users']:
            print user['name']
            if 'id' in user:
                print "  id: %s" % (user['id'])
                print "  active: %s" % (user['active'])
            else:
                print "  is not a user"
    else:
        print 'The call failed.'
except urllib2.URLError as e:
    print e
except Exception as e:
    print e
```