[http] refresh and delay

Delay: Between two requests within the same thing. Refresh: between refreshing the same channel.

Refresh: 300s, delay 1000ms:

t=0: request channel 1
t=1: request channel 2
t=2: request channel 3
t=300: request channel 1
t=301: request channel 2
t=302: request channel 3

And so on.

Please note that channels with the same stateExtensiob are refreshed with one request.