Changes

• Merged System category
• Added device classes to system sensors
• Added management URL to system web interface
• Added firmware version to system category
• Added entity categories
• Added update device class for firmware update sensor
• Convert uptime to new HA style
• Added iot_class
• Fixed some devices having manufacturer name "detect"
• Fixed empty comments as tracker entity name (hash as first character)
• Added measurement state class to traffic sensor
• Updated device_state_attributes to use extra_state_attributes
• Changed DEVICE_CLASS_* attributes to device classes