* fadd cover entity and device with mocked commands
* add cover features and update its open percentage
* execute command to the cloud instead of mocking change of shutter state
* test iotty cover commands and insertion
* fix post payload
* refactor introducing common entity from which cover and switch inherit
* move more properties to base class
* use explicit values instead of snapshots
* move iotty device initialization to base entity
* move device info from property to attribute
