Long press option for Shelly
Hi!

Today I've found that in shelly's web-interface now available new feature - Long Press
![image](https://user-images.githubusercontent.com/49816779/82837852-035dfa00-9ed3-11ea-88e5-e8f52835993c.png)
So I'd like to suggest new feature:

for one physical device (Shelly 1) to homekit interface should be added two items:
A) one logical switch - manages relay to on|of
B) one virtual button - takes long press and starts it's own scenario (programable over standard homekit interface) 
![image](https://user-images.githubusercontent.com/49816779/82838555-43be7780-9ed5-11ea-9fc6-fb7d7a721677.png)

For Shelly 2.5 can be two options (depending on what can be realised):
a) 2 relay switches and two virtual buttons for long presses respectively 
or
b) 2 relay switches and 1 virtual button for long press and long press 2 settings
![image](https://user-images.githubusercontent.com/49816779/82838710-b0d20d00-9ed5-11ea-9d2e-0785f9c399e1.png)
