200. Other agent modules and improvements

Switch is the simplest agent module, intended to be a template to help develop more complex modules.

I've started working on a module to monitor aquariums.

Other current ideas include:

• an improved Switch module to allow setting schedules to turn on/off the power outlet according to schedules (one shot, hourly, daily, weekly, monthly, yearly, anything is possible obviously)
• a module that can emit IR commands to control IR devices from your (non IR) phone, or remotely when you are not home
• a leak detection module to warn you of leaks
• a fume detection module to warn you of fires
• a movement detection module to warn you of intrusion

Many improvement ideas are listed in the two projects set in this repo, one for the master, and another one for the agents