v0.5.16: Fix duplicate entities and power factor

• Fix #52: Fixes power factor being off by 100x.
• Fix #51: @malakudi discovered a bug in how unique ID versions were handled. This caused the unique ID V1 behaviour to be treated as V0. For those of you that have serial numbers that are the same in the first 10 characters, I recommend removing and re-adding the config entry. People that haven't restarted since installing the integration will get duplicate entities upon upgrading (sorry!), feel free to remove the Unavailable ones.
• Gateway time now uses device class timestamp

Full Changelog: v0.5.14...v0.5.16