use blocking API to create Pub/Sub commands

[daTokenizer]

Add some sort of pub/sub mechanism to wrap POLL - waiting for some sort of "reactor" pattern or background tasks in Redis (maybe this should be a module).. right now this functionality can be w achieved by using this python script, the task is to add a blocking command named WATCH that duplicates the behaviour of the script.

Suggested syntax:

> REDE.WATCH <dehydrator_name> <channel/stream> [Hz]

where [Hz] is an optional parameter that would define the frequency in which to POLL the dehydrator <dehydrator_name> and publishes them on channel <channel> or streamed on stream <stream>