Add prototype application

[sebb7]

This is a prototype application. I am conscious that it lacks a lot of features but I wanted it only to send email when temperature is exceeded.

To make it works on GRISP I had to:

1. connect over wifi (link),
2. add config to grsisp release: extend args in grisp.ini.mustache with:
   -config {{release_name}}/releases/{{release_version}}/sys.config
   (idea get from slac grisp channel and specialists),
3. configure gen_smtp: in my prototype all configuration is included in config/sys.config; I was not able to make DNS work properly on GRISP so smtp relay addres must be added directly as ip tuple.

With this steps GRISP board should connect to your wifi and send email when temperature goes out of the given limits.

Working features in my prototype:

• temperature measurment via DS18B20 temperature sensor,
• temperature alarm after exeeding limit via simple email sending (for now simple temperature average is calculated from one minute time window; alarm is send after status changes from normal to below or above; status returns to normal only when temperature exceeds values from config file: lower_limit + normal_status_return_limit for below status or upper_limit - normal_status_return_limit for above status),
• simple backup in one of the event handlers state (no saving into file on sd card).

Lacking features:

• tests (everything was tested by me manually),
• file backup,
• correctly working GRISP DNS,
• proper world time on GRISP board (for now 1988 with app start).

Let me know what do you think about this basic proof of concept.