Buttons should not retain in MQTT

Export max system check for build configuration

WebUI checkboxes improvements

update supported devices

supported devices update

typo

png to jpg

Conflicts:
	code/espurna/data/index.html.gz
	code/espurna/static/index.html.gz.h
	code/html/custom.js

Conflicts:
	code/espurna/data/index.html.gz
	code/espurna/static/index.html.gz.h
	code/html/custom.js

Debug console on web

Additional Travis build coverage

general update

typo & add model no

* images for the devices
* optimized images
* fixed typo in ech1560

Improved version, where you can set the expected reaction on MQTT disconnection separate for every relay on the SWITCHES page of the web interface

logic for determining travis builds is already in build.sh

Fixing build for #643