'version_info' of oswl isn't sent to collector

iso - 8.0-570

Steps:
1. Deploy any cluster
2. Create some 'vm' through Horizon
3. Change in nailgun settings.yaml next values as below:
COLLECTOR_ACTION_LOGS_URL: "http://fuel-collect-testing.vm.mirantis.net/api/v1/action_logs/"
COLLECTOR_INST_INFO_URL: "http://fuel-collect-testing.vm.mirantis.net/api/v1/installation_structure/"
COLLECTOR_OSWL_INFO_URL: "http://fuel-collect-testing.vm.mirantis.net/api/v1/oswl_stats/"
COLLECTOR_PING_URL: "http://fuel-collect-testing.vm.mirantis.net/api/v1/ping/"
OSWL_COLLECT_PERIOD: 0
4. restart nailgun container

5. Enter to nailgun db and check 'version_info' field is present for oswl
select * from oswl_stats where resource_type='vm';
id | 6
cluster_id | 1
created_date | 2016-02-17
updated_time | 13:54:43.871297
resource_type | vm
resource_data | {"current": [], "removed": [], "modified": [], "added": []}
resource_checksum | 97d170e1550eee4afc0af065b78cda302a97674c
is_sent | t
version_info | {"release_version": "liberty-8.0", "release_os": "Ubuntu", "release_name": "Liberty on Ubuntu 14.04", "fuel_version": "8.0", "environment_version": "8.0"}

6. Check data for that master node in analytics
http://fuel-stats-testing.vm.mirantis.net/api/v1/json/oswls/22d78936-c1d7-4a78-b9cd-c2a325dad66b

Expected result - 'version_info' for oswls is present and not empty

Actual result - 'version_info' is empty because it wasn't sent from master node