[ros] Get info, status of devices via iot_bridge

[130s]

Split from #100

Get status of devices in a certain group on openHAB https://github.com/corb555/iot_bridge/issues/5#issuecomment-310937219 (e.g. ROS, but shouldn't be limited to it).

• [x] on openHAB, create ROS groups -> https://github.com/130s/hut_10sqft/issues/146
• [x] Figure out rest protocol to set status (since it looks like that's what IotCommands.update_server wants to do.
• [ ] Get status via iot_bridge for devices in any group on openHAB
• [ ] Get status via iot_bridge for any Items on openHAB
• [ ] Modify iot_bridge to get status from openHAB of any designated Items.
• [ ] Modify iot_bridge to send commands to any designated Items on openHAB.

[130s]

• [ ] Figure out rest protocol to set status (since it looks like that's what IotCommands.update_server wants to do.

From API page, where you can send rest command on a web browser, I was able to send a command (an item yahooweather_weather_berlin_humidity, which is type "Number", with a randomly chosen value 77):

Curl
curl -X PUT --header "Content-Type: text/plain" --header "Accept: application/json" -d "77" "http://130s-rpi2:8080/rest/items/yahooweather_weather_berlin_humidity/state"

Request URL
http://130s-rpi2:8080/rest/items/yahooweather_weather_berlin_humidity/state

Response Body
no content

Response Code
202

Response Headers
{
  "date": "Thu, 06 Jul 2017 03:27:01 GMT",
  "content-type": "application/json",
  "content-length": "0",
  "server": "Jetty(9.2.19.v20160908)"
}

So maybe a Group item cannot be modified.