* Add tests + some fixes
Fixes:
- [utilization] cpu_total_load returns `None` if one load is 0
- [storage] volume_disk_temp_avg + volume_disk_temp_max were global, not volume related
Add:
- [storage] env
- [storage] storage_pools
Changes:
- api.password is now private
- api.storage_url is now private
- use API_KEY on each of APIs/services
* Fix encoding
* Use future division
* Add test_disk + test_volume to check error handling cases